Objective: To identify patterns of asthma control and treatment in Australian adults with asthma. Design: Cross-sectional web-based survey, conducted 1–27. November 2012. Participants: Adults with current asthma, at least 16 years of age, drawn randomly from a web-based panel and weighted to reflect national population proportions for people with asthma. Main outcome measures: Asthma Control Test (ACT) scores; health care utilisation; medication use. Results: 2686 participants completed the survey (57.1% female; median age group, 40-49 years). Mean ACT score was 19.2 (95% CI, 18.9–19.3), with asthma classified as “well controlled” for 54.4% of participants, “not well controlled” for 22.7% and “very poorly controlled” for 23.0%. 60.8% reported using preventer medication (mostly combined inhaled corticosteroid/long-acting 2-agonist) during the previous year. 23.4% had made at least one urgent visit to a general practitioner concerning their asthma, 10.0% at least one emergency department visit. Urgent consultations were more common for “very poorly controlled” than “well controlled” asthma (adjusted odds ratio, urgent GP visits 5.98 [95% CI, 4.75–7.54] and emergency department visits 2.59 [95% CI, 1.91–3.53] respectively). Participants were classified according to asthma symptom control and frequency of preventer medication usage: Those with “well controlled” asthma included Group A (40.0% of participants) who used preventer medication infrequently (less than 5 days a week) or not at all, consistent with mild asthma, and Group B (14.7%), who used it at least 5 days a week. Uncontrolled asthma symptoms were reported by Group C (19.7%) despite regular preventer use, and by Group D (25.7%), who used none or little. Conclusions: This study provides the first data about asthma control and its relationship with treatment in a large representative Australian population. The findings highlight significant preventable asthma morbidity in Australia.