A cohort of 1041 men who were discharged from the hospital with a diagnosis of acromegaly were examined for subsequent cancer. With a mean follow-up time of 8.3 years, an increased rate of cancers of the digestive organs was observed (27 cases; standard incidence ratio [SIR], 2.0; 95% confidence interval [CI], 1.3 to 2.9). Rates were elevated for cancers of the esophagus (7 cases; SIR, 3.1), stomach (4 cases; SIR, 2.5), and colon (13 cases; SIR, 3.1). The increased risk of colon cancer in acromegaly is consistent with previous clinical reports and suggests opportunities for etiologic research and early cancer detection. It would seem prudent to also evaluate this risk in current research on the use of growth hormone in older individuals to increase muscle mass and reduce body fat.