Following the clinical observation that there appeared to be an association between shigellosis and male homosexuality, the medical records of 113 patients at The New York Hospital were reviewed retrospectively. Of the 38 males studied who were between the ages 19 and 61, seventeen were homosexual (44-7 per cent.). Only one of the matched controls was homosexual. Of the men with shigellosis who had a history of foreign travel, 10 per cent. were homosexual; however, among the patients without a travel history, 57-1 per cent. were homosexual (P less than 0-05). For male patients with shigellosis who do not have an appropriate travel history, the physician should expand his epidemiological investigation to include sexual contacts. Men and women who perform rectal intercourse should be cautioned to abstain from this activity until their stool cultures are negative for shigella. If a male patient with shigellosis is homosexual, he should be screened for other sexually transmitted diseases such as syphilis, gonorrhoea, hepatitis B, and amoebiasis.