© 2020 The Authors. Cancer Medicine published by John Wiley & Sons Ltd. Background: Studies show that patients make lifestyle changes soon after certain solid tumor diagnoses, suggesting that this may be a teachable moment to motivate and promote healthy behaviors. There is a paucity of data regarding changes made after a diagnosis of a hematologic malignancy. Methods: A cross-sectional study of 116 patients at a community oncology center who completed anonymous questionnaires was performed. Questions addressed lifestyle choices made with respect to smoking, alcohol consumption, recreational drug use, diet, and exercise habits before and after diagnosis of a hematologic malignancy. Support systems utilized, including psychiatry services, were also assessed. Results: Patients exhibited significant reduction in smoking behavior (Χ2 = 31.0, p < 0.001). 82.4% (n = 14) of one pack per day smokers quit between the time periods, with nearly all smokers showing a reduction after diagnosis. Alcohol use overall did not change significantly, however, 10.3% (n = 12) of patients reported quitting drinking completely between time periods. Changes in dietary intake and exercise were not statistically significant overall. Utilization of external support systems correlated with improved diet as well as decrease in total smoking years. Conclusions: This study demonstrates that patients exhibited significant lifestyle changes after being diagnosed with a hematologic malignancy. Clinicians should take advantage of this ‘teachable moment’ to educate patients about positive health behavior changes. Advances in cancer therapeutics have led to an increase in cancer survivors, this education is crucial in reducing the risk of developing chronic comorbidities as well as secondary malignancies.