Peyronie’s disease is relatively common in the general population and in men who have undergone a radical prostatectomy. It produces curvature and sometimes constriction of the penis from scar tissue that develops in the penis. This scar tissue is less elastic than the normal tissue and thus does not increase in length and circumference with erection as much as it should. The most common cause of Peyronie’s is believed to be vigorous sexual activity without a firm erection that causes trauma to the tissues, specifically, rupture of small vessels with hemorrhage into the tissues and subsequent scarring. However, Peyronie’s disease can also occur in men who are not sexually active. The reason for this condition is not completely known. Also, there may be a genetic susceptibility to Peyronie’s disease. There is no known cure for Peyronie’s disease. It has been treated by a variety of methods, including vitamin E, para-amino benzoic acid (Potaba), cortisone-like drugs, radiation therapy, and, more recently, with injections or creams containing a medicine called verapamil. Severe cases require surgical removal of the4 scar tissue and filling the surgical defect with a vein graft or other tissue substitute. When surgery is required, there is a substantial risk for impotency unless a penile prosthesis is also inserted. Therefore, I usually advise “watchful waiting.” With time, scar tissue matures and stretches, and often the curvature will improve with time. However, this time course may be a period of up to three years. In the meantime, it is important to take care to avoid injury to the penis by avoiding “athletic” sexual activity and ensuring that there is adequate lubrication during intercourse.