Investment in the prevention of employee offences is relatively low in comparison with resources deployed to combat other types of crime. Chief among the reasons for this deficiency are the difficulty in tackling employee offences from a preventive perspective and the lack of available information to evaluate the efficacy of existing preventive measures. On the basis of data collected from more than 2000 Swiss firms operating in the financial and commercial sector, this article classifies the most common strategy types used by firms to prevent employee offences, estimates their efficiency and identifies the structural, environmental and organizational factors affecting their operation.