AbstractEffects of ritanserin on agonistic behavior of isolated mice exhibiting aggressive or nonaggressive behavioral strategies were studied in pair‐wise encounters with group‐housed opponents. An ethological approach to behavioral scoring is adopted, which allows for examination of the profiles of individual subjects. Although the data generally support the view that ritanser in has little effect on offense or defense in male mice, the stimulation of pre‐aggressive behavior (threats, alerts, tail rattles) was detected insomenonaggressive mice. © 1995 Wiley‐L