This study examined if 2-week free nicotine replacement therapy (NRT) would be more effective than 1-week free NRT to help smokers quit smoking at 6 and 12 months. In a single-blinded randomized controlled trial design, 562 Chinese smokers who attended a smoking cessation clinic in Hong Kong, China, were randomly allocated into two groups (A1 and A2): A1 (n = 284) received behavioural counselling with free NRT for 1 week; A2 (n = 278) received similar counselling with free NRT for 2 weeks. All subjects received printed self-help materials to support their quitting efforts. A structured questionnaire was used for data collection, including pattern of NRT use and self-reported 7-day point prevalence quit rate at 6 months and 12 months. Among the participants, the mean number of cigarettes smoked per day was 18.8 (SD = 10.9). By intention-to-treat analysis, 7-day point prevalence quit rates were not significantly different between A1 and A2 groups at 6-month (27.5% versus 27.3%; P = 0.97) and 12-month (21.1% versus 21.2%; P = 0.98) followup. The findings suggest that two-week free NRT was not more effective than 1-week free NRT to increase smoking cessation rate among Chinese smokers.