Cytotoxic chemotherapy dosages are traditionally calculated according to body surface area (BSA). No guidelines exist for chemotherapy dosing of acute myeloid leukemia (AML) patients at extremes of weight. We investigated the efficacy and safety of chemotherapy dosed according to BSA based on actual body weight (ABW) among under/normal weight, overweight, and obese AML patients. AML patients (excluding acute promyelocytic leukemia) treated with anthracycline and cytarabine-based remission induction chemotherapy from 2002 to 2009 at Cleveland Clinic were divided into three body mass index (BMI) groups: under/normal weight (BMI 24.9), overweight (BMI 25.0-29.9), and obese (BMI 30.0). Among 247 AML patients, 81 (33%) were under/normal weight, 81 (33%) were overweight, and 85 (34%) were obese. Complete remission (CR) rates were similar among these groups (69.1, 79.0, and 76.5%, respectively; P 5 0.321), as was median survival (10.7, 16.7, and 14.2 months, respectively, P 5 0.352) and 30-day mortality (3.7, 2.5, 7.1%, respectively, P 5 0.331). There was no difference among groups in days to neutrophil or platelet recovery, hospitalization days for induction chemotherapy, and bacteremia. After adjustment for confounders (age, sex, BMI, white blood cells, cytogenetic risk, etiology, and bacteremia), overall survival was significantly shorter for normal weight compared to overweight (P 5 0.006) and obese (0.038) patients. Response rates and adverse events were not significantly different among AML patients of all weight classes when induction chemotherapy was dosed according to ABW. Induction chemotherapy in these patients can be safely dosed using ABW. Am. J.