A study on the prevalence of intestinal parasites in a group of homosexual men, attending a sexually-transmitted diseases clinic in Glasgow, was undertaken. Of 118 men examined over an eight-month period, four, one of whom had symptoms of dysentery, were found to be infected with Entamoeba histolytica. Cysts of Iodamoeba buetschlii were also found in the stool of one of these men. A further two patients had giardiasis, and 11 men had enterobiasis. The importance of an awareness of these conditions is discussed.