Temporal patterns of embryonic metabolism integrate ontogenetic changes in the energetic costs of growth and maintenance. Unlike most other chelonians, which show a peaked pattern of embryonic metabolic rate (MR) over time, turtles of the family Emydidae have been depicted with unimodally increasing patterns. We incubated eggs of the emydid Chrysemys picta picta under standard conditions at 30°C and serially measured rates of oxygen consumption. Five eggs showed clear decreases in MR before hatching; two others that hatched during MR measurements showed increases in MR associated with muscular activity. MRs of hatchling turtles were lower than those of prehatching embryos for at least 60 days, suggesting persistent costs of biosynthesis in yolk-dependent late-stage embryos and early hatchlings.