This study compares the thermal transfer and rewarming characteristics of heated aerosol inhalation (HAI) alone and combined with peritoneal lavage (PEL) or pleural lavage (PLL). Closed-system PEL and PLL are equally efficient at rewarming hypothermic dogs and do so at a rate approximating 6 degrees C/h/m2. Cardiovascular responses to PEL and PLL were similar. Serum electrolytes, protein, Hct, and arterial blood gases were comparable and little changed when compared in prehypothermia and postrewarming periods. HAI alone provides little heat for rewarming; more heat is realized from endogenous metabolism. Nevertheless, HAI's ease of use and possible selective cardiac rewarming characteristics argue for its inclusion with other methods of active rewarming. The use of PEL or PLL is governed by clinical circumstances.