Previous studies indicate pathophysiological and epidemiological parallels between osteonecrosis (ON) and thromboembolism (TE), two common treatment‐related morbidities in acute lymphoblastic leukemia (ALL). To elucidate risk factors for ON and explore the relationship between ON and TE, we undertook a retrospective study of children (n = 208) with ALL. Twenty‐one (10.1%) children developed ON and 42 (20.2%) TE on therapy. Thromboembolism was a significant predictor of ON on univariate (OR 8.85) and multivariate analysis, along with older age and PEGylated asparaginase. This observation supports a role for hypercoagulability in the pathogenesis of ON. Larger prospective studies are needed to further test these findings. Pediatr Blood Cancer 2015;62:1851–1854. © 2015 Wiley Periodicals, Inc.