The energy stores of human term amnion include glycogen (2.2 ± 0.3 μmoles of glucose per gram, mean ± S.E.) and ATP (0.13 ± 0.2 mM.). Histologic structure and biochemical functions were preserved during incubations of amnion for 120 minutes at 37° C, in a defined medium simulating amniotic fluid; glycogen concentrations were maintained at control values, and the concentration of ATP usually remained at 85 to 100 per cent of control values. Glucose utilization during the first 60 minutes of incubation was linear at a rate of 70.0 ± 3.0 nmoles per minute per gram of tissue. It is concluded that amnion is a highly metabolically active tissue that can be maintained in a viable state in a suitable medium.