INTRODUCTION Smoking has been reported to increase systemic inflammation. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are used as markers for systemic inflammation. In this study, the primary aim was to determine the NLR and PLR ratios in smokers. Secondly, we aimed to evaluate the relationship between the level of addiction and carbon monoxide (CO) level in the expiratory air, with these ratios. METHODS This study was designed as a single-center, cross-sectional study. It was conducted with chronic smokers aged 18–40 years, without known health problems, visiting the smoking cessation outpatient clinic of a tertiary hospital. Sociodemographic data and smoking characteristics were collected, and exhaled CO levels were measured. Complete blood count (CBC) results were recorded, including NLR and PLR. RESULTS The mean age of 247 patients was 31.2±6.1 years, with the majority of patients (68.4%) being male. While the mean value of CO was 11.6±5.6 ppm, 42.1% of cases had a high level of addiction. A statistically significant relationship was found between NLR and addiction levels, the CO level, and the amount of smoking in cigarettes/day and packs/year (all p=0.000). A statistically significant relationship was also found between PLR and addiction levels, CO level, cigarettes/day and packs/year (p=0.000, p=0.03, p=0.000, p=0.003, respectively). CONCLUSIONS We found that as the level of addiction, cigarette use, and exhaled CO levels increased in smokers, NLR and PLR increased. Our data revealed that NLR and PLR may be a simple and easily assessable proxy of systemic inflammation in smokers.