Summary 1. A blood-sucking insect, Triatoma heidemanni (endogenous in Texas), naturally infected with Trypanosoma cruzi was crushed and droplets of the infected material introduced into the left eye of an adult male negro. He contracted the infection and developed a typical case of trypanosomiasis, or Chagas' disease. 2. The chief clinical findings consisted of acute edema and hyperemia of the eyelids and conjunctivae, lasting from four to six days, enlargement of the axillary lymph nodes, and low grade fever. 3. The positive laboratory findings consisted of: a) demonstration of T. cruzi directly in the patient's blood 21, 28, 35, 42 and 63 days after the exposure; b) cultivation of T. cruzi directly from the patient's blood 21, 28, 35, 42, 49, 63 and 84 days after the exposure; c) positive animal inoculation tests for T. cruzi 21, 28, 35, 42, 49 and 63 days, and d) positive xenodiagnostic findings on 42, 49 and 63 days after the inoculation. 4. Cultural tests gave a higher percentage of positive results than other diagnostic methods. At times positive growth was obtained in vitro from 0.1 cc. of the patient's blood. 5. The present study demonstrates that the Texas strain of Trypanosoma cruzi is capable of infecting man with a disease clinically identical with that known as Chagas' disease or South American trypanosomiasis.