Impacts of the ‘Erika' oil spill on the common starfish Asterias rubens were investigated in the field, and using laboratory experiments based on contamination via food at different stages of the starfish reproductive cycle. Two months after the shipwreck, levels of hydrocarbons characteristic of ‘Erika' fuel were significantly higher in pyloric caeca and body wall of A. rubens from a contaminated site, compared with control animals from an unpolluted reference area. Concomitant immunological responses and detoxification enzyme activity (CYP1A) were enhanced in the impacted starfish, suggesting rapid biotransformation processes. This was confirmed by laboratory experiments which showed a fast PAH uptake during the 10 first days of contamination, and the start of biotransformation processes from the third day. Our study confirms benzo(a)pyrene hydroxylase activity (BPH) in A. rubens and demonstrates the influence of CYP1A in the conversion of insoluble PAHs into soluble derivatives in this species for the first time. The rapidity of decontamination could explain why starfish growth, level of motile activity, reproductive investment, energy storage and larval development were not significantly affected by these contaminants.