Law enforcement is crucial to curb unsustainable and illegal exploitation of plant and animal populations. This paper investigates the temporal pattern of illegal hunting activity and factors that influence the probability of Village Game Scouts (VGSs) arresting illegal hunters outside the Serengeti National Park (Tanzania). A total of 201 patrols were conducted during nine months between December 1998 and August 1999, and 96 illegal hunters were arrested. All illegal hunters originated from local villages within 41 km from the closest protected area border. During the dry season more illegal hunters were observed and more snares found during patrols, the increase coinciding with the annual arrival of the migratory herbivores. Logistic regression models indicated that the probability of being arrested varied seasonally and large groups of illegal hunters had a lower probability of being arrested by VGSs. This study shows that routine data collection by VGSs may provide useful baseline values from which illegal hunting activities in partially protected areas can be evaluated. Moreover, VGSs should be integrated into the existing law enforcement structure and given more resources, to ensure optimal efficiency.