An outbreak of polyarthritis, pneumonia and mastitis was encountered in a herd of goats in northern Sweden. The most obvious clinical sign was lameness, progressing to recumbency. Necropsy revealed fibrinous and suppurative polyarthritis and in some kids interstitial pneumonia. Mycoplasmas were isolated from joints and lungs and also from the udder of a mastitic goat. The strains were identified as Mycoplasma capricolum, although extensive cross-reactions with antiserum against mycoplasma strain F38 was noted.