Interaction between marine litter and cetaceans has been documented in 47 species. Specifically, filter feeding animals such as whales are susceptible to plastic contamination due to the magnitude of prey intake, which increases the risk of interaction respecting to large accumulations of microplastics (MPs). The longevity of these mammals allows them to be considered sentinel species of ocean pollution, whose exposure to plastic particles will depend mainly on the feeding behavior of the species and the level of pollution in their feeding areas. In this study, we present for the first time, evidence of MPs presence in feces of fin whale resident population of the Gulf of California collected in two feeding areas of the species: La Paz Bay (n=2; 0.103 ± 0.045 items/g) and Northern Gulf (n=1; 0.066 items/g).These results were compared in terms of abundance and composition with particles found in the analysis of surface water samples of the same areas, whose concentrations was lower for the Northern Gulf than for La Paz Bay (0.014 ± 0.006 and 0.021 ± 0.002 items.m-2, respectively). All the samples analyzed presented plastic particles, mainly fibers as the dominant item. FTIR-spectrometry analysis identified polyester as the majority polymer. The similarity in the composition of MPs between fecal samples of fin whale and surface water samples can be taken as an indication of the fin whale level exposure in different seasons and feeding areas concerning to MPs pollution that affects the region.