Radioactivity levels were determined in soil, coal and water samples collected from various locations in the south Marmara region of Turkey. The activities in samples were determined using TENNELEC LB 1000-PW detector. The absolute beta activities were observed to vary in the range 0.83 ± 0.06 - 0.50 ± 0.05 for soil in units of Bq g- 1, and 1.284 ± 0.02 - 0.079 ± 0.002 for coal samples in units of Bq g- 1 and 0.74 ± 0.05 - 0.06 ± 0.02 for water in units of Bq l- 1. In addition, gamma spectra of soil and coal samples which have highest level of beta activities were measured by using HpGe detector. 235U, 214Pb, 134Cs, 137Cs, 214Bi and 40K were detected in soil samples. 235U, 214Pb, 134Cs and 214Bi were detected in coal samples. The radioactivity levels in water samples were compared with WHO and ITS recommended levels and the literature values. © 2007 Elsevier Ltd. All rights reserved.