Loss of erection was reported in 53% of 55 male Alzheimer's disease patients with a mean age of 70.25. Loss of erection is not related to degree of cognitive impairment, age, or depression. Modal time of onset of erectile problems is concurrent with onset of Alzheimer's symptoms. Patients with erectile problems were not taking more medications overall than those without problems and had no greater overall incidence of concurrent physical problems. Thus, the evidence suggests that there may be an elevated incidence of erectile failure in patients with Alzheimer's disease as a primary problem not attributable to other age-related factors.