Many asthma patients remain uncontrolled despite guideline-based therapies. We examined real-life asthma control in Japanese patients prescribed with inhaled corticosteroid/long-acting β2-agonist (ICS/LABA). Patients (≥12 years) with ≥2 asthma diagnoses, newly initiated on medium-/high-dose ICS/LABA (Japanese asthma guidelines), from 01 April 2009 to 31 March 2015 were included, using Japan Medical Data Center Claims Database. Primary objective: proportion of patients with uncontrolled asthma in the year following ICS/LABA initiation. Secondary objectives: predictors of uncontrolled asthma and healthcare resource utilization. In medium-dose (N = 24,937) and high-dose (N = 8661) ICS/LABA cohorts, 23% and 21% patients, respectively, were uncontrolled. Treatment step up and exacerbation were most common indicators of uncontrolled asthma. Predictors of uncontrolled asthma, analyzed by multivariable Cox model, included systemic corticosteroid use, exacerbation history, comorbidities, and being female. In both cohorts, healthcare resource utilization was higher in patients with uncontrolled asthma. Over 20% patients with persistent asthma who initiated medium- or high-dose ICS/LABA were uncontrolled, highlighting unmet need for novel therapies in these patients.