A theoretical analysis for the determination of particular derived intervention levels DILs for Costa Rica is presented. DILs for 15 radionuclides for the Costa Rican diet are calculated. Assuming all foodstuffs are contaminated only with Cs-137 and a total annual intake of 355 kg y-1 instead of the 550 kg y-1 proposed by the WHO, the corresponding DIL is approximately 2000 Bq kg-1. Four possible radionuclide combinations studied that might result from a nuclear accident are: Cs-137 and Cs-134; Cs-137, Cs-134, Sr-89 and Sr-90; Cs-137, Cs-134, I-131, and I-133; Cs-137, Cs-134, Sr-89, Sr-90, I-131, I-133 and Pu-239.