OBJECTIVES: The goal of this study was to identify subgroups of the farm population that are particularly vulnerable to head injury. METHODS: A retrospective case series of hospitalized head injuries was assembled from a national registry of agricultural injuries. Vulnerable subgroups were identified based on a priori criteria and the causes and consequences of their injuries were profiled. RESULTS: Three distinct subgroups of farm people were identified as being vulnerable: (1) farm children under the age of 10, injured most frequently by a fall from a structural height (42.5%); (2) females 10-19 years, injured most frequently by large animals (68.8%), mainly horses, and (3) men over age 60 years, who were injured by a diversity of mechanized and animal-related external causes. CONCLUSION: This identification of vulnerable groups provides foundational information from which to develop and direct prevention efforts.