Insensible weightlosses (IWL) were determined in each of 24 patients with physiologically complete spinal cord transection. The patients were placed on a bed balance with an accuracy of +/- 5 g in an environmental chamber maintained at 24 degrees C. dry bulb and 17 degrees C. wet bulb temperature. Bihourly weight changes, corrected for food and fluid ingestion, were determined for a total of 24 hours. Tetraplegics have significantly lower (P less than 0.05) IWL than paraplegics. The IWL of paraplegics are in the range of IWL of normal persons reported in the literature. We conclude that a lower allowance for IWL should be for tetraplegics than for paraplegics or persons with intact spinal cords.