This study was carried out to calculate working life expectancy and its potential gains according to the degree of reduction in the specific causes of death. It sought to ascertain what potential gains in labor force longevity might be reasonably achieved through efforts to reduce mortality from injuries and poisoning, diseases of circulatory system, neoplasms and the other causes of death. The data were drawn from the three sources such as "The 1982 Causes of Death Statistics," "Abridged Life Table for Korea 1978~'79" and "The 1982 annual Report of Economically Active Population" issued by Economic Planning Board. Analytical tools used in this study were the cause-deleted life table and the Wolfbein Wool's working life table method. Partial life expectancy was adopted as an index of this study, This application will be widely used as a good demographic tool for analyzing the dynamics of labor force and causes of death. Some of the findings are summerized as follows. 1. Partial life expectancies from initial age 15, 25, and 45 respectively to terminal age 65 are 44.86, 35.59 and 17.41 year in life expectancy itself, 37.08, 32.83 and 15.21 year in working life expectancy, 7.78, 2.76 and 2.20 years in inactive life years. 2. Potential gains in working expectancy from initial age 15, 25 and 45 to terminal age 65 by the complete elimination of the specific causes of death are 1.36, 0.94 and 0.27 years in injuries and poisoning, 0.88, 0.83 and 0.54 years in diseases of circulatory system, 0.56, 0.54 and 0.37 years in neoplasms, 1.13, 1.02 and 0.58 years in the other causes of death. The relationship between degree of reduction in causes of death and potential gains in working life years is in direct proportion. The prime orders of reduction effectiveness in age groups by the causes of death are injuries and poisoning in age 15-24, the other causes of death in age 25-49 and diseases of circulatory system in age 50 and over. 3. If it were possible to reduce 25%, 50% and 75% in mortality condition 1978~'79, the average length of working life would be 38.08, 39.13 and 40.17 years in age 15, and 33.68, 34.57 and 35.44 years in age 25, and 15.67, 16.14 and 16.63 years in age 45.