From February to July in 1989, 47 patients came to our O.P.D. with the chief complaint of impotence. The average age was 48.3 +/- 10.7 y/o. We applied intracoporeal injection of prostaglandin PGE1 (20 mg); and evaluated its penile blood flow effect by color duplex scanning (Acuson 128). The erectile responses of the test showed that: 6 patients (12.8%) had normal response: and 16 patients (34%) had imperfect response. Altogether, the total positive response rate was 46.8%, and 25 patients (53.2%) showed impaired response. The onset of response was 9.1 +/- 3.6 minutes and the duration of erection was 59.2 +/- 24.7 minutes. The percentage of diameter change of both deep arteries after injection was Rt: 58.1 +/- 41.5%; left: 52.3 +/- 35.6%. The peak velocity of right cavernosal arterial flow after intracoporeal injection was 35.5 +/- 15.9 cm/sec; and that of the left side was 33.2 +/- 16.9 cm/sec. There was no correlation between the increment of peak velocity of the deep arterial flow and the erection grade. The same phenomenon was also found between the increased change in the diameter of the deep artery and the erection grade. 16 patients (34.1%) experienced tolerable pain during the procedure. Two patients (4.3%) experienced dizzines and discomfort due to venous leakage. No priapism was found. This study suggests PGE1 may be an excellent potential alternative to other vasoactive drug with less complication in the diagnosis and treatment of impotence. But the cost and stability were its shortcoming.(ABSTRACT TRUNCATED AT 250 WORDS)