The present study examined the behavior decelerative effects of combined imipramine (tofranil) and behavior modification in a severely retarded, depressed autistic man. A simple interrupted time-series design was conducted and the primary data analytic techniques consisted of modified trend analyses and dependent samples t-tests. Consistent with previous theory and scant empirical research, results indicated that combined imipramine and behavior modification significantly reduced daily episodes of self-directed and other-directed aggression. Specifically, controlling for the effects of time, the combined treatment regimen led to significant reductions in both level and slope across three topographies of aggressive behavior. Limitations of the present study and recommendations for future research were discussed. It was concluded that combined imipramine and behavior modification may be an effective strategy for reducing aggression in the developmentally disabled.