Cholecystectomy has been connected with an increase in colorectal, breast and reproductive system cancers. On 472 patients, 398 women and 74 men, cholecystectomized during the years 1951 to 1955, cancer incidence was investigated. Our results show an elevated risk of breast cancer in the female group (P = 0.016), but no significant increased risk in colorectal or gynaecologic cancer. The risk for breast cancer increased with time after operation. In our small group of men an elevated SMR was noted for colon cancer without reaching statistical significance. Possible aetiological factors for the association between cholecystectomy and breast cancer are discussed.