Although there is extensive literature related to total hip arthroplasty (THA) and total knee arthroplasty (TKA), most of this research has been devoted to analyzing patient outcomes and complications. There are no published articles to date investigating the energy expenditure of the surgeon during these procedures. Using a SenseWear Pro(2) Armband, energy expenditure measured as energy expended during 22 primary THAs or TKAs by a single surgeon was recorded. Total hip arthroplasty required a greater expenditure of energy than TKA (P < .05). No significant trend was detected when comparing patient body mass index to the number of calories used by the surgeon. The physiologic demands placed upon the surgeon for various procedures should be recognized and is an additional factor to consider when determining procedure reimbursement.