As law enforcement agencies around the world turn to community oriented and problem-oriented policing, one strategy has been to provide patrol officers with crime maps detailing crime along their beats. The strategy is meant to encourage officers to modify their patrol strategies to best control crime in the area. While this seems a promising approach, no research has assessed the use of Geographic Information Systems (GIS) crime maps by patrol officers. The current study used an experimental method involving test and control groups, as well as pre- and post-test instruments, to assess whether crime mapping information can improve officer perception and understanding of crime patterns within a jurisdiction. Forty officers were randomly split into test or control groups and were administered a pre-test concerning their background, main sources of crime information, and perception of crime patterns within their jurisdiction. Next, officers in the test group received daily, weekly, and monthly crime maps for 2 months, after which all 40 officers were administered a post-test instrument to assess changes in spatial perceptions of crime by either group of officers. Results indicated that, in general, officers do not have a good understanding of crime patterns within their jurisdiction and the introduction of crime maps did little to facilitate a better understanding of these crime patterns. Officers who received the crime maps were no more accurate than other officers in their perception of crime patterns within their jurisdiction. The author speculates that crime maps may be more useful following officer training in crime map interpretation. Future research should continue this focus with larger samples over a longer period of time. Table, figures, references, appendix