An investigation of 37 diabetics with impotence (15) or erectile difficulties (22) is presented. On average two significant abnormalities per patient were found. Ranked in order of incidence, the causes were as follows: 1) Combination of neuropathy and psychosocial factors, 2) combination of neuropathy and vascular disease, 3) peripheral neuropathy only, 4) combination of hormonal imbalance and psychosocial factors, 5) combination of three or more defects, and 6) penile vascular disease or psychosocial problems only, or hormonal imbalance combined with peripheral neuropathy.