The diet of the Peruvian Diving-Petrel (Pelecanoides garnotii) was studied from 211 stomach pumpings collected on San Gallan and La Vieja Islands, on the central coast of Peru. Planktonic invertebrates were the dominant food items representing 85.3% and 91.1% of the items ingested on San Gallan and La Vieja, respectively. The remainder of the stomach contents was fish. Euphausia mucronata was the principal prey, composing 22.1% by mass of the food ingested on San Gallan and 30% on La Vieja. Fish larval stages represented 23.6% and 19.4% of the ingested food mass on these islands, respectively. Peruvian anchovy was present in only 3.2% of the stomach contents on San Gallan and 7.8% on La Vieja. Prey consumption varied seasonally probably due to changes in resource availability. Planktonic invertebrates were the main prey in summer, while there was a high proportion of fish larval stages during in winter.