Objectives (background) <p>Atherosclerosis is a major contributor to cardiovascular disease and is strongly associated with cigarette smoking. Carotid intima–media thickness (CIMT) is a well-established noninvasive marker of subclinical atherosclerosis; however, limited evidence exists regarding the association between smoking intensity and CIMT among young adults in the Middle East. This study assessed the association between cigarette smoking and CIMT in Saudi adults aged 20–30 years compared with non-smoking.</p> Methods (setting and design) <p>This cross-sectional comparative study was conducted at Majmaah University, Saudi Arabia, between November 2025 and March 2026 and included 50 adults (25 smokers and 25 non-smokers). CIMT was measured bilaterally in plaque-free segments of the distal common carotid arteries using high-resolution B-mode ultrasonography. Three manual measurements were obtained from each artery by trained sonographers, and the mean CIMT was calculated for each participant. Group differences were analyzed using independent-samples <i>t</i>-tests. Correlations between CIMT and smoking exposure variables were assessed using Pearson’s correlation analysis, and multivariable linear regression was performed to evaluate whether smoking was independently associated with CIMT after adjustment for age and body mass index (BMI).</p> Results <p>Smokers had significantly higher mean CIMT values than nonsmokers <b>(</b>0.5404 ± 0.0218&#xa0;mm vs. 0.4695 ± 0.0222&#xa0;mm, <i>p</i> &lt; 0.001<b>)</b>. CIMT was weakly correlated with smoking duration (<i>r</i> = 0.244, <i>p</i> = 0.239) but moderately associated with daily cigarette consumption (<i>r</i> = 0.419, <i>p</i> = 0.037). Smoking remained an independent predictor of CIMT after adjustment (β = 0.0690, <i>p</i> &lt; 0.001).</p> Conclusion <p>Cigarette smoking is significantly associated with increased CIMT in young Saudi adults, supporting CIMT as an important marker for early vascular alterations.</p>