The prevalence of chronic obstructive pulmonary disease (COPD) in women is increasing worldwide. Women may have greater susceptibility to COPD progression than men, and differences in efficacy and safety of respiratory medications by gender are largely unexplored. We aimed to determine whether the response to treatment in women with COPD differed from men in a large, 1-year double-blind trial ('TRISTAN'). In a sensitivity analysis, we compared 539 male and 180 female COPD patients, who were randomized to the saLmeterol/fluticasone combination 50/500mcg bid or placebo for 12 months. Combination therapy improved pre-treatment FEV1 significantly more than placebo in women by 152 ml (95% confidence interval 95-208) and in men by 127 ml (94-159). Similarly, a reduction in COPD exacerbation rates of 31% in women (9-48%) and of 23% in men (8-35%) was observed. Combination therapy reduced COPD exacerbations requiring treatment with oral corticosteroids by 36% in women and by 41% in men. Finally, combination treatment produced a better improvement in health status than placebo with a decrease in the SGRQ scores in women by -2.3 (-4.6 - 0.1) and in men by -2.1 (-3.5 to -0.8). No gender interaction was found for any outcome. Treatments were well tolerated with no difference in the frequency of adverse events in women and men. In this trial, therapy with the salmeterol/fluticasone combination produced significant improvements compared to placebo on all main endpoints and the magnitude of these improvements was similar for both men and women.