ABSTRACT Thyroid glands maintained by isolated perfusion have been used for studies in metabolism, micro-circulation and tumour angiogenesis. Recent work is described. Thyroid metabolism can be studied for brief periods of 4–5 hours, after which there is progressive parenchymal damage. Pulsatile flow, and anti-coagulated whole blood or platelet-rich plasma provide for optimum perfusion conditions at normothermic temperatures. There is gradual degeneration of capillary endothelium in every isolated thyroid perfusion. For this reason, tumours implanted into these organs, fail to become vascularized. This failure of angiogenesis in the isolated perfused organ, has been demonstrated to stop tumour growth at 1 to 2 mm in diameter. The isolated perfused thyroid gland has also been used to elucidate the role of platelets in nurturing capillary endothelium. Platelets appear to play an essential role in the prevention of endothelial degeneration and its sequelae under normothermic perfusion conditions.