This paper describes the explanatory model of green tobacco sickness (GTS) held by migrant and seasonal farmworkers in North Carolina and compares it with a research-based biobehavioral model. GTS is a form of acute nicotine poisoning that affects individuals who work in wet tobacco fields. It is characterized by nausea, vomiting, headache, and dizziness. There are no standard diagnostic criteria for GTS; clinicians must diagnose it based on a combination of symptoms and exposure risk. GTS resembles pesticide poisoning, but treatment is quite different. Many farmworkers in tobacco today are Spanish-speaking immigrants from Mexico with limited experience in tobacco work. In-depth interviews about GTS were conducted with 23 Hispanic farmworkers in central North Carolina to explore their understanding of the problem. Workers generally attributed the symptoms to other aspects of working in tobacco, such as pesticides or heat, rather than nicotine. They cited many of the same risk factors identified in the biobehavioral model, such as wet work conditions and inexperience with tobacco work. Prevention and treatment include a combination of exposure avoidance and common medications. The symptoms of most importance to farmworkers were insomnia and anorexia, both of which impaired the ability to work. This jeopardized their income, as well as their work security. If health care providers understand the explanatory model held by farmworkers, they will be more effective at diagnosing and treating GTS and be better prepared to teach patients how to prevent future episodes.