We have observed 4 cases of extraintestinal cancer complicating Crohn's disease (CD). They included renal cancer, urinary bladder cancer, ovarian cancer and myeloma. A review of the literature showed a considerable number of reports of extraintestinal cancer complicating CD with a total of 75 further cases. The significance of those and our cases is discussed. The possibility of extraintestinal cancer must be kept in mind following patients with CD. Our report suggests there may be a nonnegligible risk of extraintestinal cancer, particularly genitourinary tumor, in CD. The causal relationship, if any, remains undetermined.