© 2019 The composition, distribution and source of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments and tissues of the mussel Modiolus capax from three sites with increasing anthropogenic impact in La Paz Bay on the Gulf of California, were determined. Levels of total PAHs in sediments (18.9-94.5 ng/g dw) were below the effect range low for marine sediments at all sites. PAHs in mussels (147.01-271.09) were higher than in sediments and similar to mussels from other moderately contaminated sites. The origin of PAHs was predominantly petrogenic, attributed to port activities and a thermoelectric plant. The mussels of Las Pacas and Pichilingue showed the lowest condition indexes and some organisms with the presence of benzo(a)pyrene in their tissues, which is among the most toxic hydrocarbons and may represent a risk to human health. However, this study only represents a baseline for future studies, which are necessary to dismiss risks to human health and the ecosystem.