Six tetraplegic (T) and 4 paraplegic (P) subjects underwent a 20-minute pre sauna phase (30 degrees C DB; 65% RH), and an up to 15-minute sauna (85 degrees C DB; less than 10% RH), followed by a 15 minute post sauna phase (30 degrees C DB; 65% RH). During all phases subjects wore a bathing suit and remained supine on a hospital trolley. Heart rate (HR) and blood pressure (BP) were recorded during all phases. Rectal temperature (Trec) was measured by a probe (AD590) inserted approximately 14 cm into the rectum. Oral temperature (Toral) also utilising (AD590) circuitry was recorded simultaneously with Trec. Skin temperature (Tsk) (AD590) was measured on the head, chest, right thigh and right calf. Forehead sweat rate (SR) was determined from dew point temperature (Tdp). A catheter was inserted into a dorsal hand or foot vein and venous blood was withdrawn at selected times and analysed for haemoglobin (Hb) and haematocrit (Hct), and the separated plasma was analysed for glucose (Glu), sodium (Na+), potassium (K+) and chloride (C1-). Venous blood sampled just prior to entering and just prior to leaving the sauna, was analysed for adrenalin (A) and noradrenalin (NA) using high performance liquid chromatography. For both groups HR rose significantly during the sauna with a significant decline in HR for the P group during the post sauna phase. There were no significant changes in systolic BP for either group. A significant decline in diastolic BP was found for the T group during the post sauna phase. There were no episodes of syncope.(ABSTRACT TRUNCATED AT 250 WORDS)