Growth of a leptospire isolated from frog kidney tissue was stimulated by the addition of glucose to a bovine albumin polysorbate 80 medium, did not grow in the absence of polysorbate 80, but did respire on a complex of polysorbate 80 and bovine albumin. Growth was completely inhibited by 2-deoxy-D-glucose in a glucose-free bovine albumin polysorbate 80 medium. A requirement for vitamins B₁ (thiamine) and B₁₂ was demonstrated. Oxythiamine and the thiazole fragment of thiamine were nearly equivalent to vitamin B₁ in growth supporting activity while thyamine pyrophosphate, thyamine monophosphate, the pyrimidine fragment of vitamin B₁ and pyrithiamine were much less effective. The isolate was continually propagated at 31.5, 29, 20, 15, and 9 C. Growth could be initiated at 33.5–34 C. but serial subculture failed. Growth was not initiated at 35 u.c. The organism had a cellular but no extracellular tributyrinase.