Purpose: Chronic insomnia is a prevalent health problem in primary care associated with morbidity and health service utilization. Mindfulness Based Cognitive Therapy (MBCT) is a therapeutic approach developed over the last few decades although only few large randomized control trials have been conducted in those with primary insomnia. This study aimed to evaluate the effectiveness of MBCT in treating primary chronic insomnia in primary care by comparing with a psycho-education control (PEC) group in the community.Methods: This was a single-blinded, randomised, controlled clinical trial. Eligible participants were Chinese adults (18 years of age or above) with diagnosed chronic insomnia at baseline assessment. Subjects were randomly assigned into MBCT group (intervention) and PEC group (control), were followed up for six months. Primary outcome was changes in the score of a validated Chinese version of 7-item Insomnia Severity Index (ISI). Paired t-test was used to examine between-group differences. Analysis was performed by intention-to-treat. Results: We recruited 216 subjects with an average age of 56.05 (SD 9.39), where 77.0% [116/216] were female. At baseline, there was no significant differences between MBCT group [N=110] and PEC group [N=106] in terms of age (p=0.450), gender (p=0.250), ISI scores (17.67, SD 3.70 for PEC; 17.94, SD 3.70 for MBCT; p=0.623). At eight-week (follow-up rate 93.6% [88/94] for MBCT group, 93.5% [87/93] for PEC group), there was a significant decrease in ISI scores in MBCT group (-4.26, SD 3.87) when compared to that of PEC group (-2.81, SD 4.08) (p=0.041). Conclusion: Results demonstrated that MBCT programme may significantly reduce the insomnia severity among Chinese subjects with chronic insomnia when compared to PEC group in the primary care group. The study suggested that MBCT programme may be an evidence-based treatment options for subjects with chronic insomnia in primary care although longer follow-up is needed to evaluate the sustainability of the effects.