['Undesirable weight gain often follows smoking cessation. We investigated whether weight gain after smoking cessation is greater in those with higher levels of inflammatory markers.', 'We studied weight gain and risk of a large gain (> or = 90th percentile) over 3 years in a cohort study of 11,687 U.S. men and women, 45 to 64 years old, with focus on the 2664 who continued and the 493 who quit smoking.', 'Among new quitters, adjusted weight gain for those in the highest (vs. lowest) quartile of leukocytes was 0.56 kg/yr more (95% confidence interval, 0.17 to 0.95); for those in the highest (vs. lowest) quartile of fibrinogen, 0.60 kg/yr more (95% confidence interval, 0.27 to 0.92; p = 0.02 and 0.001 for adjusted smoking status by leukocyte and smoking status by fibrinogen interaction terms, respectively). In adjusted analyses, the odds ratio for a large gain associated with quitting (vs. continuing) was 6.2 for those in the highest quartile of leukocytes vs. 2.2 for those in the lowest leukocyte quartile (p = 0.03 for smoking status by inflammatory marker interaction). Similarly, the odds ratio for a large gain associated with quitting was 4.5 in the highest fibrinogen quartile vs. 2.5 in the lowest (p = 0. 09 for the interaction term).'] Do inflammation markers predict increased weight gain in smoking quitters?