Objectives : To improve decreased erectile function as well as impotence, caused by physical fatigue, psychologic stress, too much alcohol and smoking, medication like antihypertensives, and geriatric change, by the prescription of BOWONDAN. Methods : 18 male-volunteers with decreased erectile function who are married 30 to 59 years old, were studied about the difference of a sexual function between before and after taking BOWONDAN 3 pills a day for a month. The results of IIEF(International Index of Erectile Function) and AVSS(Audio-Visual Sexual Stimulation) were reviewed statistically with paired samples t-test. Results : Based on the IIEF, 13(81.25%, p<0.01), 9(56.25%, p<0.05), 9(56.25%, p<0.05), 9(56.25%, p<0.05), 7(43.75%, p<0.05) and 15(93.75%, p<0.01) volunteers were improved in erectile function, orgasmic function, sexual desire, intercourse satisfaction, overall satisfaction and total score respectively, among 16 volunteers excluding 2 due to a false measurement. Through the Rigiscan of AVSS, 11 (68.75%, p<0.1)volunteers were improved in base tumescence, among 16 volunteers excluding 2 due to a false measurement. Conclusions : As a result of our work, BOWONDAN is expected to take effect to treat or improve both impotence and decreased erectile function.