Radiopreservation using gamma radiation is widely in use as a safe method for extending the shelf life of shellfish. This study explored the consequences of different doses of gamma radiation (0.5 kGy, 1.0 kGy and 2.0 kGy) on various tissues of Scylla serrata at cellular and nuclear level, with the aid of electron microscopy and DNA comet assay. The highly radio exposed (2.0 kGy) pyloric muscles showed a reduction in sarcomere length, disordered organization with expanded gap between adjacent myofibrils, ruptured sarcotubular system, mitochondrial swelling with crushed cristae, significant increase in nucleus size coupled with less dense nucleoplasm, etc. Comet assay on tissues such as muscle, hepatopancreas and testis irradiated with 2.0 kGy radiation also revealed a significant degree of nuclear damage by gamma irradiation in a dose-dependent manner. The tail length of the comet showed a tissue-specific tolerance level. The present study clarified the precise dose of irradiation as 1.0 kGy and the results can be relevant for commercial purposes to qualitatively categorize the irradiated crabs. © KONINKLIJKE BRILL NV, LEIDEN, 2019