One hundred and seventy six men with histories of anal intercourse were studied to determine if there was a correlation between the clinical features, cytological findings in the mucosal secretions, and the histological appearance of the rectal mucosa. The presence or absence of gastrointestinal symptoms did not differentiate between patients with and without proctitis. Sigmoidoscopy was normal in each of the 117 men with normal rectal histology. Macroscopic abnormalities were evident in the mucosa of nine of 11 men with infective proctitis, and sigmoidoscopy was normal in 40 of the 48 men with chronic proctitis. Cytological examination was often useful in detecting infective proctitis but not chronic proctitis.