Asthma in older adults is associated with high rates of morbidity and mortality; similarly, asthma can be severe enough among younger adults to warrant disability benefits. Reasons for poor outcomes in both groups of patients may include discontinuation and lack of adherence to controller therapies. To examine characteristics and treatment patterns of US Medicare patients initiating omalizumab for asthma, and factors associated with its discontinuation and adherence. A retrospective claims database analysis of Medicare beneficiaries with asthma initiating omalizumab treatment was carried out. The primary outcomes were omalizumab discontinuation (gap in use ≥90 days) and adherence (proportion of days covered ≥0.8) over a 12-month follow-up. Multivariable regressions were used to examine factors associated with omalizumab discontinuation and adherence. Of the 3058 Medicare patients initiating omalizumab for asthma (mean age, 62.7 years), 36.9% discontinued omalizumab and 60.6% were adherent. Discontinuation rates were 32.7% and 42.8%, and adherence rates were 65.4% and 53.9%, for disabled and older Medicare patients, respectively. Patients aged 65 to 69 years and 70 to 74 years had significantly lower odds of discontinuation (odds ratios [95% CI], 0.66 [0.46-0.93] and 0.62 [0.43-0.89], respectively) and higher odds of adherence than did patients aged 80 years or older. Compared with patients receiving low-income subsidy, patients not receiving low-income subsidy had lower odds of discontinuation (0.66 [0.52-0.83]) and higher odds of adherence (1.52 [1.20-1.93]). Greater numbers of preindex evaluation and management physician visits and comorbid rhinitis were associated with lower odds of discontinuation and higher odds of adherence. More than 60% of Medicare patients with asthma continued and were adherent to omalizumab over a 12-month follow-up. Patient age, low-income subsidy status, and the numbers of evaluation and management physician visits were among factors associated with treatment adherence and discontinuation. Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.