Streptomycin by intermittent intramusc. injn. was slightly but temporarily effective in the treatment of 3 out of 6 rabbits with established acute syphilitic orchitis in total dosage of 24,000 to 240,000 U. per kg. of wt., but complete cures were not observed in any of the animals receiving total dosages of 24,000, 120,000 and 240,000 U. per kg. by intramusc. injn., over a period of 8 days.