Recent studies have suggested an excess of coxarthrosis (osteoarthrosis of the hip joint) among Swedish farmers. The prevalence of coxarthrosis in the city of Malmö has previously been studied by coincidental examination of the hip joints on colon roentgenograms. The present study estimates the prevalence of coxarthrosis in farmers by examining the hip joint on roentgenograms of the colon and urinary tract. Fifteen-thousand farmers and farm workers affiliated with the Swedish Farmers' Safety and Preventive Health Association and all farmers aged 40 years or older in the Swedish country of Ostergötland were questioned about previous roentgenographic examinations. Four hundred thirty-five colon examinations and 465 urograms were available and scrutinized by the same physician. Forty-five of 565 male farmers and farm workers, aged 40-64 years, were found to have roentgenographic signs of primary coxarthrosis, compared with ten of 1250 men in the corresponding age group in the urban population of Malmö. The difference represents a rate ratio of 12 with a 95% confidence interval of 6.7 to 21.4. There was no difference in the prevalence of coxarthrosis among the female farmers and women in the urban population. The result suggests a relationship between coxarthrosis and farm work in men.