The aim was to evaluate the possible acute effects of cigarette smoking on erectile function, estimated by combined (I.C.I.) test and duplex examination of the penile vessels after Glina and co-workers (1988). The present study included 25 patients complaining of erectile dysfunction between 20 and 60 years, who are known to be smokers. First session, the patient was asked not to smoke any cigarettes 12 hours before attending the examination room. For the second session, the patient was asked to smoke two cigarettes. After Intracorporael injection of vasoactive drug, the peak systolic velocity in both cavernosal arteries was measured using a color Doppler ultrasound machine. Results obtained from both sessions for each patient were compared. A significant change in the mean value was seen for all patients, it can be concluded that smoking does have an acute effect, in addition to its chronic effect. This acute effect is rather influenced by several factors. Among these is the effect of the number of cigarette intake per day, the age of subjects on nicotine dependence, the presence of accompanying disease as Diabetes Mellitus.