Leptospira interrogans serovar pomona was successfully isolated from cattle urine in the western Transvaal after an abortion storm had occurred. Direct inoculation of EMJH medium proved the most successful method. The selective agent, 5-fluorouracil, was most effective in controlling contamination when used at the 0,4 mg/ml level. The strain isolated was pathogenic in hamsters, but specific lesions and the leptospirae were seen only where overwhelming infection occurred.