OBJECTIVE: The objective of this study was to determine the feasibility of field-based biomonitoring of heat-related illness (HRI) phenomena in Florida farmworkers. The authors determined feasibility through participant interviews regarding acceptability, data capture, recruitment and retention, and observed barriers and challenges to implementation. METHODS: Study participants were employed in fernery operations in northeast Central Florida where ornamental ferns are grown and harvested in a seasonally high-heat environment. In this pilot, a total of 43 farmworkers participated during summers 2012 and 2013 and measurements included body core temperature, heart rate, energy expenditure, urine and blood osmolality, and self-reported HRI symptoms. RESULTS: Data capture was approximately 90%. Participants reported that the study methods were nonobtrusive to their work, and that they were comfortable with study measures. CONCLUSIONS: These results open possibilities for characterizing HRI utilizing physiologic biomonitoring in vulnerable occupational groups.