Compared to men, women may be at greater risk for smoking-related diseases and have greater difficulty quitting smoking. Sex differences in medication response could guide treatment for smoking cessation to improve women's quit rates. We conducted a meta-analysis of the 14 placebo-controlled nicotine patch trials (N = 6,250) for which long-term (6 months) clinical outcome results could be determined separately by sex. This analysis updated a meta-analysis of 11 of these trials that found no significant sex differences due to nicotine patch. The increase in quitting due to the nicotine vs. placebo patch was only about half as large in women as in men. Pooled absolute quit rates at 6 months for nicotine and placebo patch, respectively, were 20.1% and 10.8% in men, and 14.7% and 10.1% in women. The odds ratio for quitting due to nicotine vs. placebo patch was lower in women (OR = 1.61) than in men (OR = 2.20), with an interaction odds ratio of 1.40 (95% CI = 1.02-1.93, p = .04). This sex difference did not vary significantly by whether or not formal counseling was provided. Poorer outcomes in women vs. men treated with nicotine patch suggests that increasing the quit rates of women smokers may require supplementing patch treatment or use of other medications.