The natural (226Ra, 228Th, 232Th and 40K) and anthropogenic (137Cs) radionuclides concentrations in three crustaceans species (Penaeus monodon, Metapenaeus monoceros and Panulirus versicolor), collected from the bay of Bengal, were determined with an aim of assessing any internal radiation hazard due to consumption of the shell fishes and establishing a database for radioactivity levels of the species. Very low level of radioactivity was observed in all the species. The average activity of 226Ra observed in P. monodon was 1.21 ± 0.27 Bq kg–1 fw; in M. monoceros was 0.70 ± 0.08 Bq kg–1 fw, and in Panulirus versicolor was 1.04 ± 0.09 Bq kg–1 fw. The activity of 232Th observed in these species was 1.30 ± 0.37, 0.76 ± 0.34 and 1.32 ± 0.70 Bq kg–1 fw, and 228Th was 0.55 ± 0.26, 0.31 ± 0.14 and 0.74 ± 0.22 Bq kg–1 fw, respectively. The average activity of 40K observed in these species was 12.56 ± 1.18, 6.38 ± 1.02 and 10.07 ± 1.52 Bq kg–1 fw, respectively. The activity of radiocaesium (137Cs) was below detection limit. The results indicate that the natural and artificial radionuclides observed in three crustaceans species are safe for human health. A significant relationship was observed between 226Ra and 232Th in both the P. monodon (r = 0.839, p ≤ 0.05, df = 4) and the Panulirus versicolor (r = 0.906, p ≤ 0.05, df = 4).