Resting energy expenditure (REE) was measured by indirect calorimetry during allogeneic and autologous bone marrow transplantation in order to evaluate the evolution in allogeneic and autologous recipient patients. REE values obtained with indirect calorimetry and compared with values using the Harris-Benedict formula were different. Evolution of REE during aplasia were significantly different in autologous and allogeneic recipients with an increase 11.5 ' 10.8 cent for autologous and a decrease of - 7.3 ' 8.9 cent in allogeneic bone marrow transplantation (BMT) patients. There were no differences in nutritional status and REE before BMT, at discharge and 1 month after discharge between the two groups but all patients had inflicted damage on their nutritional status at discharge from hospital after BMT. However, these patients differed because of the decrease in oral nutritional intake and an increase in the length of aplasia and hospital stay in allogeneic patients. Currently, there is no proof that recommendations for nutritional interventions or results of nutritional investigations in allogeneic BMT can be extrapolated in autologous patients. Harris-Benedict formula does not estimate the energy expenditure of patients submitted to massive chemotherapy and BMT with enough precision because of the great differences in individuals.