The radiological hazard of naturally occurring radioactive material in Homa Mountain found in southwestern Kenya was investigated after 210 point measurements and 44 samples were analyzed. In situ measured average outdoor absorbed dose rate in air using survey meters was found to vary from 154.8 to 2280.6 nGy h-1. Using HpGe detection system radioactivity concentrations mean (range) values measured for 40K, 226Ra and 232Th were 915±3 (64–3017), 195±8 (17– 1447) and 409±4 (23-1369) Bq kg-1, respectively. The calculated range, of the annual effective dose for a person living in Homa Mountain area, varied from 28.6 to 1681.2, with a mean of 470.4 µSv. All calculated average radiological indices, namely Radium equivalent, Representative level, Gamma activity, External and Internal hazard were higher than the limits set by various national and international bodies. These results imply Homa Mountain region is a high background radiation area.