We used the PRISMA to guide our literature review and analysis (Moher et al.,2009). We included RCTs of smoking cessation that report abstinence rates for adult smokers aged ≥50 years, published in English between January 1, 1990 and January 28, 2015. Three main inclusion criteria were: (1) reporting results from smoking cessation RCTs; (2) presenting smoking abstinence either in the form of proportions or the numbers of abstainers and sample sizes;(3)including adult smokers aged ≥50 years, or reporting abstinence rates by age groups that included those ≥50 years.