The radiation induced products of tryptophan (TRP) were determined in gamma-irradiated egg white, chicken meat and shrimps using RP-HPLC and electrochemical detection. A two-step hydrolysis with proteinase K and carboxypeptidase A was developed to release the radiation products from egg white and chicken meat and with proteinase K and pronase E from shrimps. The four hydroxytryptophan isomers (OH-Trp) were identified and quantified as radiation products in all samples. The amounts ranged between 0.02 and 1.97 mg/kg protein. A significant difference between irradiated and unirradiated samples was found for irradiation doses of more than 3 kGy for egg white and chicken meat. For shrimps no significant increase of OH-Trp isomers was measured up to a radiation dose of 5 kGy.