In an effort to lower healthcare costs, this study was undertaken to evaluate the utility of routine postoperative (PO) laboratory studies and determine whether abnormalities alter patient (PT) care. This was a retrospective review of 105 PTs undergoing elective curative resection for colorectal cancer. A serum electrolyte and liver panel and a hematologic panel were drawn in all PTs. OF 8749 total laboratory values obtained, 5894 (67%) were normal. Two of these (0.03%) elicited a therapeutic intervention. Of the 2004 values that were low (23%), 103 (5.1%) elicited a therapeutic response. Of the 851 that were high (10%), 21 (2.5%) elicited a therapeutic response. Of 2089 preoperative laboratory values, 252 (12%) were abnormal, but in only 15 incidences in 9 PTs was any action taken. Three PTs required potassium supplementation and 6 PTs were transfused packed red blood cells before surgery. In the PO period 2603 laboratory values of 6660 obtained (39%) were abnormal. Of these, 735 (28%) were high and 1868 (72%) were low. Twenty of 735 (27%) high values triggered a therapeutic response that most commonly required administration of insulin for elevated serum glucose in 17 of 197 occasions in five diabetic PTs. On three occasions potassium was removed from intravenous fluids. Five of 275 (1.8%) low calcium values were treated in five patients. Potassium was replaced in 17 of 32 occasions in 14 patients where it was low. In this group of PTs, PO serum potassium, hemoglobin levels, and serum glucose in diabetics were the only values important in making therapeutic decisions. If laboratory studies can be streamlined into only those necessary, substantial savings in health care will be seen without sacrificing quality medical care.