A large proportion of the residential and nursing home population is mentally ill. The causes for increased prescription of psychotropic drugs other than mental disorders have been discussed. This study presents data on the role of the individual's characteristics and institutional conditions on psychotropic drug use in residents of residential and nursing homes. Therefore the psychotropic drug use of 4 old-people's homes in Leipzig (Germany) was reviewed. Sociodemographic characteristics and a number of behavioral patterns of the residents were examined. Regression analysis revealed associations of age, gender and certain behavioral patterns (e.g., agitation, insomnia with nightly disturbances) and psychotropic drug use. Beyond that, psychotropic drug use varied among the 4 institutions' practices. Further research should be aimed at gaining insight into the interplay of these individual and institutional influences on psychotropic drug use in order to develop specific interventions to optimize treatment.