Renal pyruvate dehydrogenasea activity was measured in suspensions of kidney cortex tubules from fed rats after incubation with various concentrations of Ca2+, 3'5' cyclic AMP or adrenalin. At certain concentrations these agents all decreased pyruvate dehydrogenasea activity and increased glucose formation from pyruvate. There appeared to be some interdependence between the effects of Ca2+ and 3,5, cyclic AMP on pyruvate dehydrogenasea activity. Effects of adrenalin on pyruvate dehydrogenasea activity were no longer observed when palmitate was included in incubations. The possibility that regulation of pyruvate dehydrogenasea may indirectly contribute to the control of gluconeogenesis by influencing pyruvate metabolism is briefly discussed.