We studied the diet of Markham's Storm Petrel Oceanodroma markhami on Paracas Peninsula and La Vieja Island, central Peru, in 1996, 1999 and 2000. A total of 95 samples was collected from adults captured in mist nets at breeding colonies, using the water-offloading technique. The diet was composed of fish (54% by mass), cephalopods (36%) and crustaceans (10%). Among the fish, Peruvian Anchovy Engraulis ringens was the main prey (27.2% of the total mass), followed by fish of unknown identity (16.7%). The Pelagic Squat Lobster Pleuroncodes monodon was the main crustacean prey (9.4%); the oceanic octopus Japetella sp. was the most frequent cephalopod eaten. Prey composition varied among years, before and after El Nño 1997/98. Fish was the main prey in samples during 1999, when anchovy was first observed in the diet (43% by mass). Cephalopods were the main prey in 1996 (44%) and 2000 (84%). Fish prey suggests both inshore and offshore feeding, while cephalopods suggest offshore feeding only. The observed pattern of the diet of the Markham's Storm Petrel indicates opportunities feeding.