In the present study we assessed the resting energy expenditure of 30 free-feeding control and methylcholanthrene-induced sarcoma-bearing rats prior to and following surgical removal of the tumor. Tumor-bearing rats demonstrated carcass wasting and massive tumor growth. The resting energy expenditure data in our model suggest that neither the presence and growth of a tumor nor its removal significantly change resting energy expenditure beyond the normal range for non-tumor-bearing rats. We suggest that in the partition of energy costs between host and tumor, both carry a similar input, proportional to their relative weight, into the total combined resting energy expenditure of host and tumor.