During the period from 1957 up to and including December 1975, the surgical clinic of Nijmegen admitted 82 patients with the diagnoses of diverticulosis and diverticulitis of the colon: the diagnosis of diverticulosis was made in 16 cases; in 17 diverticulitis was diagnosed and these patients were treated by conservative methods. Forty-nine patients were subjected to operation for diverticulitis. Of the patients treated conservatively, none died; of those treated by operation, three (6%) died. There were nine patients with peritonitis and three with ileus who required emergency surgery. As a matter of principle these patients were treated in several stages; none of them died.