Eighty-seven cats from the Glasgow area were investigated to determine the prevalence of leptospiral infection and possible resultant disease. Eight (9-2 per cent) of the cats reacted serologically with the antigens of three serovars. Five of the cats were seropositive to Leptospira hardjo, two to L autumnalis and one cat serocon-verted to L icterohaemorrhagiae. A paired serum sample indicated a recent infection in one of the cats. The major clinical sign shown by this cat was ascites. Four of the cats were from rural areas. This appears to be the first report of a serological survey of leptospiral infection in cats in the Glasgow area.