Agricultural workers are exposed to a variety of hazards that increase their risk for dermatitis. Nevertheless, the prevalence, patterns, and risk factors for dermatitis have not been well characterized among farmers in the United States. We assessed the prevalence and risk factors for dermatitis among 382 male farmers and 256 wives of farmers in Iowa using a cross-sectional study design. From 1992 to 1994, we collected data on potential risk factors and dermatitis. The results showed that 9.6% of male farmers and 14.4% of wives of farmers reported dermatitis during the previous 12-month period. In multivariable models, a history of allergy (odds ratio [OR], 8.2; 95% confidence interval [CI], 2.0 to 33.3) was strongly associated with dermatitis among male farmers. Among wives of farmers, some college education (OR, 3.4; 95% CI, 1.1 to 9.9) and exposure to petroleum products (OR, 3.1; 95% CI, 1.3 to 7.0) were associated with dermatitis. These results can be used to form preventive efforts in controlling farmwork-related exposures.