Primate trypanosomiasis is now known to occur in macaques in an area in South Asia measuring 3000 miles east to west and 2600 miles north to south. The countries involved are Indonesia, Taiwan, Malaysia and India. Human trypanosomiasis is known from Malaysia and India. More than one kind of trypanosome is involved. Studies will be made on: the epidemiology of the trypanosomiases of the area, the relationship if any between human and monkey trypanosomiasis, characterization of the trypanosomes involved, evaluation and use of diagnostic tests for trypanosomiasis and on utilization of the trypanosomes involved for studies in cell biology to which they lend themselves particularly well.