The purpose of this study was to clarify the connection between aggressive and sexual behavior with the aid of testosterone propionate (TP) and parachlorophenylalanine (PCPA). Previous studies have indicated that aggressive and sexual behavior are positively correlated, and it has been suggested that both behaviors are related to the level of general arousal. Testosterone has documented effects on both aggressive and sexual behavior. It has been hypothesized that these effects are due to an increased level of general arousal. If this is the case, aggressive and sexual behavior could be restored by administration of drugs excitating the central nervous system, e.g., PCPA. The present study examined the effects of TP and PCPA on aggressive and sexual behavior in gonadectomized male mice. Control animals were injected with sesame seed oil or saline. The level of aggressiveness was assessed by means of dyadic tests with gonad-intact male opponents. For the sexuality tests, a receptive female was placed in the home cage of the experimental male. The results showed that male mice injected with PCPA were more aggressive than the males of the other groups, while the TP-exposed males expressed the most sexual activity. Compared to the control group, the PCPA and TP groups were more active in both the aggression and the sexuality tests. These findings lend support to the hypothesis that the earlier documented correlations between aggressive and sexual behavior could be due to both behaviors being dependent on a certain level of general activation.