The aim of this paper is to provide information on the analysis of stable isotopes obtained from bones of marine and terrestrial fauna used as potential food by hunter‐gatherers on the northern coast of Santa Cruz province (Argentine Patagonia). The results from the isotopic ecology are analysed to contribute to dietary interpretations of the human populations who lived in this area. The mean of terrestrial resources is −19.1‰ ± 1.8‰ and 9.2‰ ± 2.6‰ for δ13C and δ15N, respectively. Meanwhile, marine resources recorded a mean of δ13C −12.5‰ ± 1.2‰ and δ15N of 19.4‰ ± 2.4‰. The analysed human samples come from different types of burials dated mainly in the Late Holocene. The δ13C and δ15N isotopic values on human remains suggest the existence of different diets during the Late Holocene, including people who consumed mainly marine, terrestrial, and mixed proteins, with a range between −18‰ to −10.4‰ and 12.4‰ to 23.4‰ for δ13C and δ15N, respectively. Some of these isotopic values, which indicate marine diets, are the highest recorded for Patagonia. The influence of the marine spray on the terrestrial trophic chains is suggested for the Patagonian Atlantic coast, evidenced by higher values in the δ15N of guanacos from the coast in relation to others studied from the hinterland.