Removal of the spleen may possibly affect functions of the immune system. Cancer risk following splenectomy was evaluated by performing a linked register study in Denmark from 1977-89. From the Hospital Discharge Register we identified 1103 patients splenectomized after traumatic rupture of the spleen and 5212 patients splenectomized for various malignant or non-malignant disorders and both groups were followed for cancer occurrence in the Danish Cancer Registry. No increased risk for cancer was observed among patients who underwent splenectomy due to trauma. In contrast, there were excesses of a number of specific cancers among patients who underwent splenectomy for non-traumatic reasons, but to a large extent this could be explained by factors related to the underlying disease and/or treatment of the disease.