We wish to report briefly the cases of 4 patients with erysipeloid of Rosenbach treated with sulfanilamide. Three of the patients responded promptly to sulfanilamide alone and were well in from three to five days. The fourth patient did not respond to sulfanilamide by mouth but did respond to the immune serum injected locally at the advancing border of the lesion. All patients were white men. Two received the infection from a puncture wound obtained from a fish fin, 1 from a beef bone and 1 from a hog bone. The duration of the eruptions varied from eleven days to three and one-half weeks. In 3 of the 4 patients the eruption involved approximately one third of the surface of the skin of one hand. In the fourth patient nearly all of the hand was involved. The 3 patients that responded to sulfanilamide were instructed to take 10 grains (0.64