An accurate assessment of the energy needs of hospitalized patients is necessary to fulfill caloric requirements, yet avoid inducing complications associated with excessive energy provisions. The objective of this study was to compare actual energy needs as determined by indirect calorimetry with several methods for estimating energy needs. These included the Harris-Benedict Equation (HBE), HBE plus factors for stress (ie, trauma, surgery, cancer), Wilmore's nomogram, and estimates using 25 and 35 kcal/kg. One hundred nineteen parenteral nutrition patients were studied. HBE or the method of 25 kcal/kg was found to be most accurate in predicting energy needs. Stress factor adjustments of HBE significantly overestimated energy needs when compared to indirect calorimetry, as did the use of Wilmore's nomogram and the factor of 35 kcal/kg.