BACKGROUND: The transition from family tobacco production to dependence on hired labor has placed migrant and seasonal farmworkers (MSF) at risk for green tobacco sickness (GTS). No previous studies of GTS have focused on MSF. METHODS: One hundred and forty-four Hispanic MSF working in tobacco production in North Carolina were surveyed to obtain self-reports of GTS, preventive behaviors, and treatments. RESULTS: Forty-one percent reported having GTS at least once during the summer. Most had taken no precautions to prevent GTS. Ninety-six percent of those with GTS had tried to treat it. Antinausea medications were the most common treatments. Only 9% sought medical treatment; 7% lost work time. CONCLUSIONS: The incidence of GTS obtained by interviewing MSF is much higher than that in other studies, which have relied on rates of medical treatment or farmers' reports for their workers. MSF constitute a population at risk for GTS who have little control over work conditions to prevent GTS or seek treatment.