BackgroundMost asthma patients in Vietnam have poorly controlled asthma. Besides reasons related to the health care system and health care providers, knowledge on the self-management of patients has also contributed to this situation.PurposeTo assess knowledge on asthma self-management among adult asthma patients in Ho Chi Minh City.Patients and methodsA cross-sectional study with convenience sampling was conducted among 322 ambulatory patients using questionnaires filled in via a face-to-face interview. The questionnaires enquired about: 1) sociodemographic details, 2) the Global Initiative for Asthma 2017 criteria of asthma control, 3) the Asthma Control Test, and 4) the Asthma Self-Management Questionnaire (ASMQ). Knowledge on asthma self-management was determined by the ASMQ score. The relationship between this knowledge and demographic factors and asthma control levels was determined.ResultsThe knowledge on asthma self-management was low, with a mean raw ASMQ score of 4.3 (maximum 14); this is equivalent to 30 in a transformed score (maximum 100). Only 0.3% of these patients had good knowledge, 16.2% had adequate knowledge, and 83.5% had poor knowledge. Of all participants, 52% stated erroneously that asthma can be cured, 30% were confused about control and rescue medications, 68% failed to correctly describe the inhalation technique, and only 15.5% could answer correctly about the management of an exacerbation. Although most participants had poor asthma control, the higher the patient’s level of control, the better the ASMQ score. Conversely, patients with better knowledge of asthma self-management (ASMQ score ≥50) had better asthma control based on the Asthma Control Test score. Also, a higher education level was associated with more knowledge on asthma self-management.ConclusionIn these patients, the level of knowledge on asthma self-management was low and significantly correlated with the level of asthma control. There is a clear need to improve knowledge in order to improve asthma control in Vietnam.