Pre-operational survey at Kalpakkam coast, indicated elevated gamma background radiation levels in the range of 100–4000 nGyh-1 over the large tracts of the coastal sands due to the presence of pockets of monazite mineral in beach sands. In view of the prevalence of monazite, a systematic gamma spectrometric study of distribution of natural radionuclides in soil and beach sand samples collected from the terrestrial and coastal environment of Kalpakkam was performed and concentrations of primordial radionuclides such as 238U,232Th and 40 K and anthropogenic radionuclide 137Cs were determined. The concentrations of 238U,232Th and40Kin soil samples were 5–71, 15–776 and 200–854Bqkg1dry, respectively. In beach sand samples,238U,232Th and40 Kcontents varied in the range of 36–258,352–3872 and 324–405 Bqkg -1dry, respectively. The total absorbed gamma dose rate in air due to the presence of 238U,232 Th and 40Kin Kalpakkam soil samples varied between 24 and 556 nGyh-1 with a mean of 103 nGyh-1. The contribution to the total absorbed gamma dose rate in air in the decreasing order was due to the presence of 232Th (76.4%), followed by 40K (16.9%) and 238 U (6.7%) in Kalpakkam soils. However, in beach areas of Kalpakkam, the presence of 232 Th in beach sand contributed maximum (94.0%) to the total absorbed gamma dose rate in air followed by 238 U (4.7%) and minimum contribution was by 40K(1.3%).137 Cs in Kalpakkam soils ranged from ≤1.0 to 2.8 Bq kg-1 dry, which was 1–3 order of magnitude less than the concentration of primordial adionuclides in soil.