A series of case-control studies have been carried out to compare farmers reported to the Illinois State Cancer Registry (ISCR) with other males reported to the ISCR between 1986 and 1988. Data on the number of farms in each Illinois county producing given agricultural commodities were obtained from the United States Census of Agriculture and used as surrogate exposure indicators. Employment as a farmer was found to be associated with cancer of the eye [odds ratio (OR) = 6.49, 95% confidence interval (CI) = 1.78, 23.71], lip (OR = 4.42, 95% CI = 2.46, 7.94), prostate (OR = 1.15, 95% CI = 0.99, 1.35) and leukaemia (OR = 1.51, 95% CI = 1.01, 2.25). Wheat and soybean production were found to be positively associated with leukaemia. Hay and beef production were found to be positively associated with cancer of the prostate.