This article furthers our understanding of the cost of coronary artery bypass graft (CABG) surgery by analyzing the extent to which preoperative correlates of cost differ among hospitals. A total of 2828 patient who underwent bypass surgery at 3 hospitals (2 teaching and 1 nonteaching) were analyzed. The preoperative correlates of direct variable cost (marginal cost) were determined by ordinary least squares regression. Age, urgent/emergent surgical priority, previous CABG, and chronic obstructive pulmonary disease (COPD) were significant contributors (P < .05) to cost in all hospitals, but overall, there were many differences. The major contributor to cost was non-white race (31.3%) at teaching hospital A, previous CABG (30.5%) at teaching hospital B, and preop insertion of intra-aortic balloon pump (IABP) (35.9%) at the nonteaching hospital. The number of significant risk factors also differed. Preoperative characteristics that contribute to cost can be quite different among hospitals and therefore results from one hospital cannot be broadly generalized to others.