This study examines the relationship between diabetes knowledge and compliance among Chinese with non-insulin dependent diabetes mellitus (NIDDM) in Hong Kong. A cross-sectional design was used to collect data through structured self-report interviews based on validated scales assessing diabetes knowledge, compliance behaviours and demographic data. The Diabetes Knowledge Scale was used to sample knowledge in the major areas of basic physiology of diabetes and general principles of diabetes care. Compliance level was assessed by using the Compliance Behaviour Questionnaire, inspection of patients' feet and the value of HbA1c. A convenience sample of 52 Chinese with NIDDM receiving out-patient diabetes care participated in the study on a voluntary basis. Descriptive and correlational statistical analyses were used to analyse the data. The findings indicated that there was no association between diabetes knowledge and compliance. There was a gap between what the patients were taught and what they were actually doing. Most of the patients gained higher marks on factual knowledge on diabetes but lost marks on the application of knowledge to their real life situations. Strategies are suggested to close the 'knowledge-action gap' and increase patients' motivation and ability to comply with the health regimen.