Background: Cessation-related weight gain and weight concerns are common among smokers and have a negative impact on quitting. Obese smokers tend to gain more than the average amount of weight and also have lower quit rates. This article describes the prevalence of obesity and weight concerns among smokers calling a state quitline in the United States. Results: Among 3972 smokers using a state quitline, 33.3% were obese, 30.2% overweight, 33.3% normal weight and 3.2% under-weight; a total of 60.6% were concerned about cessation-related weight gain. Compared with non-obese callers, obese callers were more likely to be female, Hispanic, non-White and heavier smokers. Conclusions: This is the first study to report data on body weight and weight concerns of smokers calling a national quitline. Given the lower quit rates among obese and weight-concerned smokers, and the burden of smoking and obesity, there is an opportunity to develop new treatment approaches for this at-risk population.