Cognitive functions in 53 elderly men who underwent a transurethral prostatectomy were assessed pre-operatively and 4 days and 3 months post-operatively. Thirteen patients had a preference for one particular type of anesthesia, and the remaining 40 were randomly allocated to receive either spinal or general anesthesia. Cognitive function was not different between the groups receiving different types of anesthesia at either time point and did not decrease post-operatively. No pre- or perioperative variable could distinguish the subgroup of patients who had a post-operative decrease of 2 points or more on the Mini-Mental State Examination. No difference in post-operative performance was found in the patient groups with pre-operative Mini-Mental State Examination scores above or under their age-specific norm. It is concluded that neither hospitalization nor the two forms of anesthesia investigated cause a decrease in cognitive function in elderly men.