Trypanosome infection rates in tsetse, Glossina pallidipes Austen in five areas along the Kenya coast were studied for 2 years (1980)(1981)(1982). The total percentage infection rates were 12.62, 7.24, 9.50, 7.86 and 7.97 for Ukunda, Diani, Muhaka, Shimba Hills and Mwalewa, respectively. The respective values for males were 3.13, 4.16, 5.17, 5.03 and 8.13. Overall there were more trypanosome infections due to; Trypanosome congolense followed by T. vivax and T. brucei, although these varied among the localities. The age of the flies, their feeding patterns and regular use of chemoprophylaxis in local cattle were the main factors affecting infection rates.