A single dose of DGAVP (2 mg) and a chronic treatment of 2 weeks (1 mg/day) were given to male and female volunteers by the intranasal route. Memory, mood, vigilance, and attention were tested starting 60 min after treatment. Initial storage of abstract words was improved in the males but not in the females after chronic treatment with DGAVP. This effect persisted after discontinuation of treatment. Initial storage and learning of concrete words were not affected by treatment with DGAVP. Chronic, but not acute, treatment with DGAVP reduced the reaction time for scanning of digits in a memory comparison task (Sternberg paradigm) in both sexes. No treatment effects were found for visual memory, vigilance, attention, mood, or blood pressure. The present study indicates a sexual dimorphism in the effect of DGAVP on certain memory processes.