Isolation, characterisation and antibiotic sensitivity of 18 strains of Corynebacterium pyogenes from different animals have been reported. All the C pyogenes isolates uniformly differed from the typical strains of this species by the utilisation of trehalose and their failure to acidify maltose. The majority of the strains failed to grow in the presence of 0.1 per cent potassium tellurite. Tuberculosis-like lung lesion in a seven-day-old calf yielded one of the strains of C pyogenes. Histopathological changes in the calf lung have also been described.