Hypothermia develops during the intra-operative period partly as a result of disordered thermoregulation induced by anaesthesia, and partly because of the nature of the operation or injury and the surgical environment. Both the hypothermic state and the consequences of physiological attempts to return the core temperature to normal, which take place during the postoperative period, are associated with non-beneficial effects. Attempts to prevent an intra-operative decline in core temperature are a part of anaesthesia management. However, most of the traditional options available are inefficient or ineffective, especially if used as a single intervention and particularly in adults. This study evaluates the performance of a new device, the forced-air convective warmer, in the management of the postoperative hypothermic state. Results show that the device made a significant difference to the thermal state of a group of hypothermic postoperative patients when compared with a hypothermic control group, but only if used for at least 2 hours after the operation.