This study was conducted to identify the effects of caffeine or combinations of caffeine and iron or vitamin E on the lipid and protein components or blood chemistry levels of the serum as well as the total homogenate, mitochondrial and microsomal fraction of the rat(Sprague-Dawley, female) liver. Chronic test were conducted to determine those effects. The chronic test was conducted by dividing rats into 5 groups according to the type of drugs and dosages administrated as follows; the control(group A), and group B was given 25mg/kg caffeine orally once daily for 30 days, group C was given 50mg/kg caffeine orally once daily for 30 days, group D was given 25mg/kg caffeine and orally ferric chloride once daily for 30 days and group E was given 25mg/kg caffeine and 25mg/kg vitamin E once daily for 30 days. The concentrations of glucose, urea nitrogen, uric acid, creatinine, total protein, albumin, A/G ratio, triglyceride, total cholesterol, HDL-cholesterol, free fatty acid, phospholipid as well as the activities of alanine aminotransferase(ALT), aspartate aminotransferase(AST) and alkaline phosphatase(ALP) were measured in the serum of each experimental groups. The concentrations of the carbonyl group and malondiaidehyde(MDA) and the patterns of the SDS-PAGE(Sodium Dodecyl Sulfate - Polyacrylamide Gel Electrophoresis) and fatty acid compositions in free fatty acids and phospholipids were analyzed to determine the oxidative damages and metabolic changes on the lipid and protein components in the serum, and total homogenate, mitochondrial and microsomal fractions of the rat liver. The results obtained from this study were summarized as follows; 1. Body weights of groups B, C, D and E were significantly decreased(p < 0.01) in comparison with that of the control in the chronic test. 2. The concentrations of serum glucose in groups B(124.5mg/dl), C(130.1mg/dl), D(122.1mg/dl), E(119.3mg/dl) were significantly higher(p < 0.01) in comparison to that of the control(101.5mg/dl). But, there were no significant differences in the concentrations of urea nitrogen, uric acid, creatinine, total protein, albumin and A/G ratio in comparison to that of the control. 3. The concentrations of total cholesterol and HDL-cholesterol in serum of groups B(69.6, 53.4mg/dl), C(73.0, 56.3mg/dl), D(68.9, 51.1mg/dl) and E(68.2, 51.3mg/dl) were significantly higher(p < 0.01) in comparison to that of the control(52.6, 38.8mg/dl). On the other hand, the concentrations of triglyceride in serum of groups B(45.0mg/dl), C(40.4mg/dl), D(33.8mg/dl) and E(47.2mg/dl) were significantly lower(p < 0.01) in comparison to that of the control(66.2mg/dl). There were no significant differences in the activities of ALT, AST and ALP in comparison to that of the control. 4. The concentrations of free fatty acid and phospholipid in serum of groups B(45.7, 154.4mg/dl), C(50.0, 167.2mg/dl), D(52.5, 148.4mg/dl) and E(41.1, 159.2mg/dl) were higher(p < 0.01) in comparison to that of the control(35.2, 125.3mg/dl). And the concentrations of the carbonyl group and malondialdehyde in serum of group D(1.82, 0.52nM/mg protein) were significantly higher(p < 0.01) in comparison to the control(1.53nM/mg protein). 5. The concentrations of carbonyl group in total homogenate, mitochondrial and microsomal fraction of group D(1.45, 0.94, 1.67nM/mg protein) were significantly higher (p < 0.01) in comparison to the control(1.16, 0.66, 1.27nM/mg protein). And the concentrations of malondialdehyde in the total homogenate, mitochondrial and microsomal fraction of group D(6.70, 6.10, 1.36nM/mg protein) were significantly higher(p < 0.01) in comparison to the control(5.17, 3.64, 0.68nM/mg protein). 6. As the analytical results of the fatty acid compositions of free fatty acid in serum, the proportions of stearic acid and arachidonic acid of groups B(16.52, 12.62%), C(17.52, 15.18%), D(19.73, 13.47%) and E(17.62, 13.28%) were significantly higher(p < 0.01) in comparison to the control(14.75, 7.88%), but the proportions of oleic acid and linoleic acid of groups B(12.97, 32.59%), C(10.88, 31.23%), D(12.37, 30.66%) and E(11.95, 32.41%) were significantly lower(p < 0.01) in comparison to the control(16.44, 35.12%). Otherwise, as the results of the fatty acid compositions of phospholipid in serum, the proportions of stearic acid and arachidonic acid of groups B(39.37, 16.39%), C(40.63, 17.83%), D(42.73, 15.39%) and E(39.16, 15.70%) were significantly higher(p < 0.01) in comparison to the control(37.74, 14.24%), but the proportions of oleic acid and linoleic acid of groups B(4.03, 14.38%), C(3.54, 12.38%), D(4.52, 11.68%) and E(4.29, 13.64%) were significantly lower(p < 0.01) in comparison to the control(5.53, 16.14%). 7. As the analytical results of the fatty acid compositions of free fatty acid in total homogenate, mitochondrial and microsomal fraction of liver, the proportions of oleic acid of groups B(7.8**, 8.73**, 6.88%) and C(6.89**, 7.75**, 6.58%) were lower(**:p < 0.01) in comparison to the control(8.67, 10.08, 7.81%), but the proportions of arachidonic acid of group C(22.62, 19.79, 23.71%) were significantly higher(p < 0.01) in comparison to the control(20.93, 18.47, 22.24%). And the proportions of palmitic acid of group D(25.95**, 26.16, 26.34**%) were significantly higher(**:p < 0.01) in comparison to the control(24.43, 25.42, 23.34%). In addition, the proportions of linoleic acid of group D(23.43, 25.02, 23.95%) were also significantly higher(p < 0.01) in comparison to the control(22.17, 23.75, 21.26%). The proportions of stearic acid of group D(19.87, 19.76**%) in mitochondrial and microsomal fraction were lower(**:p < 0.01) in comparison to the control(21.01, 24.18%), and the proportions of stearic acid of group E(16.71*, 19.65**%) in mitochondrial and microsomal fraction were significantly lower(**:p < 0.01, *:p < 0.05) in comparison to the control(21.01, 24.18%), and the proportions of linoleic acid of group E(25.04, 29.20, 26.48%) in total homogenate, mitochondria and microsome were significantly higher(p < 0.01) in comparison to the control(22.17, 23.75, 21.26%). 8. As the results of the fatty acid compositions of phospholipid in total homogenate, mitochondrial and microsomal fraction of liver, the proportions of palmitic acid of group D(17.58**, 18.78*, 18.23%**) were significantly higher(**:p < 0.01, *:p < 0.05) in comparison to the control(16.28, 17.22, 16.38%), and the proportions of stearic acid of group D(36.41, 37.23, 39.53%) were also significantly higher(p < 0.01) in comparison to the control(34.18, 34.16, 36.04%). But the proportions of oleic acid(3.41*, 3.11**, 3.12**%) and linoleic acid (18.03**, 15.79**, 14.74**%) of group D were significantly lower(**:p < 0.01, *:p < 0.05) in comparison to the control(oleic : 3.63, 3.72, 3.79%, linoleic : 20.03, 18.71, 18.48%). 9. In order to determine the oxidative damages to the protein in serum, mitochondrial and microsomal fraction of the rat liver, the patterns of the SDS-PAGE were identified, but the results of SDS-PAGE were not significantly different between the control and experimental groups.