Body surface area(BSA)is a parameter frequently used to calculate the chemotherapy dosage. Several different equations for predicting BSA have been developed. We examined the formula suggested for BSA calculation for 62 chemotherapy drugs where the recommended dosage was based on patient BSA. We found that the description of the formula to be used for BSA calculation was not provided in the package inserts or in the drug interview forms in the majority of cases; the BSA formula was mentioned in the guide for appropriate use of medication in only 8 of 62 chemotherapy drugs. Furthermore, we observed that the choice of formula used to calculate patient BSA caused differences in the dosage of drugs administered to patients undergoing certain oral anti-cancer drug therapies. The results ofour study indicate that clinical oncologists should pay careful attention to the formula used to calculate BSA.