Mortality of eggs and nest attendance pattern of male and female Adélie Penguins were studied in Lützow-Holm Bay, Antarctica. Twenty percent of eggs were deserted by parents and were taken by skuas soon after. Only four percent of eggs were lost from skua predation. In pairs relieving incubation routines successfully (coordinated pairs), females made the first foraging trips of 18.3 days after clutch completion, alternately males made the second trips of 10.6 days. Desertion of eggs and small chicks occurred when 1) females did not return from the first foraging trips and the mates deserted nests, 2) males did not return from the second foraging trips and the mates deserted nests or 3) males went to the first foraging trips. The males whose partners did not return from the first trips did not incubate longer than males of coordinated pairs in the first incubation spell, while females whose partners did not return from the second trips incubated twice as long as those of coordinated pairs.