1. 1. A description is given of the history of tsetse fly occupation in Southern Rhodesia and the position to-day and the outlook for the future. 2. 2. The previous history of human trypanosomiasis in Southern Rhodesia is summarized. 3. 3. The events leading up to the 1934 medical surveys are related. 4. 4. The discovery of “healthy carrier” cases of human trypanosomiasis at Gowe is described. 5. 5. A description of the natural conditions at Gowe is given. 6. 6. The bearing of the experience at Gowe on the epidemiology and control of the disease in Southern Rhodesia is discussed. 7. 7. Some tentative ideas on protozoal immunity with special reference to human trypanosomiasis are advanced.