The discovery of high concentration uranium deposit at Mkuju, southern part of Tanzania, has brought concern about the levels of natural radioactivity at villages in the neighborhood of the deposit. This study determined the radioactivity levels of 30 soil samples and 20 water samples from Likuyu village which is 54？km east of the uranium deposit. The concentrations of the natural radionuclides 238U, 232Th, and 40K were determined using low level gamma spectrometry of the Tanzania Atomic Energy Commission (TAEC) Laboratory in Arusha. The average radioactivity concentrations obtained in soil samples for 238U (51.7？Bq/kg), 232Th (36.4？Bq/kg), and 40K (564.3？Bq/kg) were higher than the worldwide average concentrations value of these radionuclides reported by UNSCEAR, 2000. The average activity concentration value of 238U (2.35？Bq/L) and 232Th (1.85？Bq/L) in water samples was similar and comparable to their mean concentrations in the control sample collected from Nduluma River in Arusha. 1. Introduction The radioactivity level from the natural radionuclides is termed as background radiation which will depend on the amount of the radioactive materials in the environment. The background radiation can be high if the environment is polluted either from man-made or natural activities. It can also be high in regions with deposit of mineral resources such as uranium ores and phosphate [1]. Materials from the deposit may be brought to the surface soil through processes such as weathering of rocks and soil formation. They can also leach into the groundwater system, contaminate it, and lead to pollution far away from the source. In Tanzania, high concentrations of uranium deposits of up to 464？ppm have recently been reported at Mkuju in Namtumbo area at Ruvuma region. This has brought concern about the level of natural radioactivity in the soil and drinking water at villages in the neighborhood of the deposit. This is because there are reports in the literature which indicate high radioactivity levels in regions near uranium deposits [2, 3]. Rabesiranana et al. (2008) in Madagascar and Sartandel et al. (2009) in India reported enhanced level of 238U and 232Th in the soil around uranium deposits as compared to the world average [2, 4]. Enkhbat et al. (2008) reported high activity concentration of 226Ra, 232Th, and 40K in soil around Gurvanbulag uranium deposit in the eastern part of Mongolia [3]. The present study has determined concentration levels of the 238U decay series and the 232Th decay series as well as 40K in soil and water from Likuyu village which is 54？km
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