The purpose of this study was to determine the tuberculin positivity rates and the incidence of sexually transmitted diseases (STDs) among a population of seasonal, nonmigrating farm workers. Participants were tested for tuberculosis (TB) sensitivity, syphilis, gonorrhea, and chlamydia. Patients were afforded follow-up even if they returned home to Mexico during the course of their treatment. We found that the TB rate (15%) and the incidence of STDs to be significantly lower than in other studies of migrant populations. We hypothesize that exposure to urban commercial sex workers who frequent many migrant camps may be involved in the transmission of TB. Further research is needed to determine the incidence of TB among commercial sex workers and the extent to which transmission occurs between these two populations. We also describe our follow-up program and recommend a closer adherence to the Centers for Disease Control and Prevention guidelines with respect to adequate health education and disease prevention.