Abstract. Miniature depth gauges were attached inDecember 1987 and January 1988 to Ad61ie penguins, Pygoscelis adeliae, breeding at Esperanza on the Antarctic Peninsula. Results from 34 birds showed that foraging penguins with eggs and with brooded and cr6ching chicks spent mean periods away from the nest of 96, 36 and 21 h, respectively, during which time means of 29.0 h (30%), 11.2 h (31%) and 2.7 h (13%), respectively, were spent under water at depths > 5 m. Time under water was positively correlated with time absent from nest. Maximum depth reached was 170 m but overall birds spent most time at shallower depths. Birds foraging for brooded chicks dived deeper than birds foraging for cr6ching chicks. Stomach-pumping indicated that the principal prey caught at this time was krill, Euphausia superba.Mean mass changes of adults during single foraging trips indicated that krill were caught at a mean rate of 7.2 g min-1 spent under water.Wilson's analysis was, however, only intended to determine gross depth-utilisation differences between sympatric Pygoscelis species, and no details on intra-specific differences were presented.We analysed results derived from depth gauges used on Ad61ie penguins breeding in Antarctica during December 1987 and January 1988. This includes a detailed re-analysis of data already presented (Wilson 1989) in addition to new data from other birds not included in the time span of Wilson's study. In this paper we consider depth utilisation by Ad~lie penguins during the course of a breeding season and present a model to attempt to determine prey capture rate by these birds. Such studies can help define the foraging niche of Ad61ie penguins. In addition, examination of temporal variability in Ad61ie penguin depth utilisation and foraging effort might lead to insights regarding the vertical distribution and local abundance of their prey, Antarctic krill.