In the present study, selenium contents for some selected food items commonly consumed in Portugal are presented. Food items, i.e., meat, fish, eggs, dairy products, cereals, fruits and vegetables were sampled from two representative markets of two different regions of Portugal territory. The selenium concentrations in the various food items have been determined by using nuclear activation analysis (NAA) in both versions instrumental (INAA) and replicate sample (RSINAA) through the short-lived nuclide 77mSe that features a half-life time of 17.5 s. The highest values were found for meat, fish and eggs (87.6–737 μg kg−1); lower values were obtained for vegetables and fruits (1.7–24.9 μg kg−1).