Suspensions of rabbit testes infected with the Nichols strain of Treponema pallidum were made to infect rabbits by intracut. injns. After 3 days, streptomycin (158-229 units/mg.) or crystalline penicillin G was injd. every 4 hrs. for 4 days. All lesions at the site of inoculation were tested for spirochetes in the dark field. All other rabbits were kept 4 months and a suspension of the popliteal lymph nodes of each was injd. intratesticularly into 2 rabbits. If the recipient''s testes remained normal, the donor was considered cured. The smallest amt. of streptomycin that cured any rabbit when given in divided doses was 79,000 units per kg. in 1 expt. and 187,000 units per kg. in another. A similar effect was obtained with 147 units per kg. of cryst. penicillin G. All control rabbits developed typical lesions.