We report the results of a cohort study of 182 seasonal and migrant farmworkers engaged in tobacco production in two North Carolina counties. Data were collected on tobacco work tasks and risk factors for exposure to nicotine, including smoking, every 2 weeks over a 10-week period during the summer of 1999. Saliva samples were collected for cotinine analysis at every contact. Salivary cotinine levels increased across the season, independent of smoking status. Multivariate analyses identified a model (R2 = 0.68) in which predictors of cotinine included greater age, later-season work, wet working conditions, smoking, and work task. Harvesting (“priming”) tobacco was associated with higher cotinine levels than other tasks. This study demonstrates that tobacco workers experience substantial work-related exposure to nicotine. The long-term effects of such exposure should be investigated.