The bignoniaceous Arrabidaea chica (Bonpl.) B. Verl. (syn. Bignonia chica), Bignoniaceae, popularly known as carajuru, puca panga, chica or pariri is very common in the Amazon region. Leaves of this plant are widely used as anti-inflammatory and astringent agents as well as remedies for intestinal colic, sanguine diarrhea, leucorrhea, anemia and leukemia. The action of the extract from leaves and stems of Arrabidaea chica on hepatic energy metabolism was investigated in the perfused rat liver and isolated mitochondria. In isolated mitochondria the Arrabidaea chica extract (0.25-1.25 mg/ml) decreased the respiratory coefficient with the substrates β-hydroxybutyrate and succinate. The activities of succinate-oxidase and NADH-oxidase were inhibited and the ATPase of intact mitochondria was stimulated. The extract also inhibited the glucose 6-phosphatase of isolated microsomes. The cellular content of glucose 6-phosphate was increased, while the level of ATP was reduced. In perfused livers the extract (0.25-1.0 mg/ml) caused stimulation of oxygen consumption, inhibition of gluconeogenesis from lactate and pyruvate and reduction of glucose release from endogenous glycogen. The results of this investigation suggest that the inhibitory effect of the extract on hepatic glucose production is mainly related to its actions on the mitochondrial energy metabolism.