The aim of this study is to evaluate the effect of actively monitored closed circuit television (CCTV) to assist police patrols with crime prevention in hot spot areas for assault. In other words, the study is an assessment of whether the implementation of police operator–controlled CCTV cameras led to fewer assaults in a nightlife area of the Swedish town of Malmo¨ . In order to evaluate the effect, the treatment area has been mapped using geographical information systems based on the space covered by operational CCTV. The research design is based on standard before–after comparison with controls used in environmental criminology. One comparison is temporal, based on days of the week, and the other is geographical, based on a density comparison of bars. Results show nonsignificant changes in the rate of assaults before and after the CCTVs, suggesting that its implementation has not had the effect initially expected on assaults.