ABSTRACT: BACKGROUND: Insomnia is a common public health problem and the prevalence and impact of insomnia in primary care attendees is not well documented in the Asian population.ObjectivesTo determine the prevalence of self-reported insomnia symptoms amongst adult primary care attendees and the association with socio-demographic factors; to ascertain the impact of insomnia on daily functioning and to describe the psychological profile of patients with insomnia. METHODS: In this cross-sectional survey, 2049 adult patients (>=18 year old) attending seven primary care clinics in Peninsular Malaysia, completed the questionnaire asking about symptoms of insomnia (defined according to the International Classification of Sleep Disorders and DSM IV criteria) daytime impairment and psychological symptoms (assessed by Hospital Anxiety and Depression Scale). RESULTS: The response rate was 86.2 . A total of 60 reported insomnia symptoms, 38.9 had frequent insomnia symptoms (>3 times per week), 30.7 had chronic insomnia without daytime consequences and 28.6 had chronic insomnia with daytime dysfunction. Indian ethnicity (OR 1.79; 95 CI, 1.28-2.49), age >= 50 or older (OR 1.82; 95 CI, 1.10-3.01), anxiety symptoms (OR 1.65; 95 CI, 1.21-2.22) and depression symptoms (OR 1.65; 95 CI, 1.21-2.26) were risk factors for chronic insomnia with daytime dysfunction. Amongst those with chronic insomnia with daytime dysfunction, 47.8 had anxiety symptoms (OR, 2.01; 95 CI, 1.57-2.59) and 36.5 had depression symptoms (OR, 2.74; 95 CI, 2.04-3.68) based on HADs score. They also had tendency to doze off while driving and to be involved in road traffic accidents. CONCLUSIONS: A third of primary care attendees have insomnia symptoms and chronic insomnia, associated with significant daytime dysfunction and psychological morbidity. By identifying those at risk of having chronic insomnia, appropriate interventions can be commenced.