The evaluation of vasculogenic impotence by color flow Doppler ultrasound after injection of intracavernous vasoactive agents allows for simultaneous visualization in real time of arterial and venous blood flow. Normal arterial blood flow parameters after prostaglandin E1 injection have yet to be standardized. Our study was initiated to evaluate blood flow parameters in a normal control population after prostaglandin E1 and visual stimulation. A total of 20 healthy male volunteers 45 to 60 years old with histories of normal sexual function was selected. All volunteers were given intracavernous injections of 10 micrograms prostaglandin E1 and received concurrent visual stimulation by means of an erotic video. All patients developed rigid erections with no complications. Using color flow Doppler ultrasound measurements were done before and after prostaglandin E1 injection of right and left superficial and deep cavernous artery diameters, peak blood flow velocities and blood flow volumes. Results (mean plus or minus standard error) showed a significant increase in diameters after prostaglandin E1 in the superficial (20% increase) and deep (70% increase) penile arteries. Blood flow volume increased 3-fold for the superficial penile arteries (from 7.3 +/- 1.4 to 20 +/- 3.5 cc per minute) and 4-fold for the deep cavernous arteries (from 3.8 +/- 1 to 12.5 +/- 1.8 cc per minute). Peak blood flow velocity increased 2-fold (from 22 +/- 3 to 46 +/- 7 cm. per second) for the superficial arteries and 3-fold (from 12.5 +/- 2 to 37 +/- 5 cm. per second) for the deep cavernous arteries. These data suggest control values for normal erectile function in middle-aged men as a 70% increase in deep cavernous artery diameter, a systolic peak blood flow velocity greater than 30 cm. per second and more than 10 cc per minute of blood flow volume. With these standards the clinician may assess, design and follow treatment strategies for vasculogenic impotence.