A growing body of epidemiological evidence suggests an association between short sleep duration and obesity. Recently, potential hormonal links have been observed that may account for the relationship. The possible connection between sleep duration and body mass index (BMI) has not been explored in rural populations. Rural populations are of interest because obesity rates are high and lifestyle patterns of nutrition, physical activity, work hours, and sleep may differ from those in urban and suburban populations. We conducted this study to determine whether short sleep duration is related to BMI and obesity in a rural population in southeast Iowa. We conducted a cross-sectional analysis of data collected in the Keokuk County Rural Health Cohort Study, 1999-2004. Study participants were from a population-based sample consisting of 990 employed adults in a rural community in southeastern Iowa. The main outcome measure was BMI. Multiple linear regression modeling was used to adjust for potential confounding variables. Self-reported sleep duration on weeknights was negatively correlated (beta = -0.42; 95% confidence interval, -0.77 to -0.07) with higher BMI after adjusting for sex, age, educational achievement, physical job demand, household income, depressive symptoms, marital status, alcohol consumption, and snoring. These data support an association between short sleep duration and higher BMI in this rural population, which is consistent with the relationship found in other settings.