Erectile dysfunction is more common than previously thought in men older than 40 years, perhaps because contributing medical risk factors increase with age. The medical history is of prime importance in outlining these factors, the most common of which are diabetes, hypertension, and smoking. Nocturnal penile tumescence and rigidity testing with a portable home monitor may be helpful in determining whether the cause of erectile dysfunction is primarily organic or psychological. Specific therapeutic measures include sex therapy, psychotherapy, treatment for alcohol or tobacco dependency, replacement of offending medications, improved glycemic control, constriction rings, vascular surgery, androgen replacement therapy, bromocriptine mesylate (Parlodel), and thyroid, adrenal, or pituitary replacement therapy. Nonspecific therapies include yohimbine hydrochloride (Yocon), use of vacuum tumescence devices, intracorporeal injections, and penile implants.