Objective: To investigate the correlation between baseline neutrophil-to-lymphocyte ratio (NLR) and changes in carotid artery intima-media thickness after antihypertensive therapy in young and middle-aged patients with essential hypertension. Method: A total of 154 untreated young and middle-aged patients with essential hypertension from the Second Affiliated Hospital of Shaanxi University of Chinese Medicine were included retrospectively enrolled from January to September 2022. Patients were divided into three groups according to NLR level, and baseline general data, biochemical parameters, baseline and internal carotid media thickness (CAIMT) parameters after 12 months of antihypertensive treatment were collected. Spearman correlation analysis and multiple linear regression analysis were used to determine the independent influences on ?CAIMT after antihypertensive treatment in young and middle-aged hypertensive patients. Result:At baseline, systolic blood pressure, smoking history, total cholesterol level, and CAIMT increased in Q1, Q2, and Q3 (all P <0.05); after 12 months of antihypertensive treatment, CAIMT decreased compared with baseline, and the degree of CAIMT change decreased from Q1 to Q3 (all P <0.05);Spearman Correlation analysis showed that CAIMT was negatively associated with NLR, systolic BP, total cholesterol (TC), age, smoking history, sex (rs = -0.569, -0.573, -0.389, -0.176, -0.551, -0.193, and P values <0.001). Multiple linear regression analysis showed that NLR, systolic blood pressure, and smoking history were independent influencing factors of CAIMT in young and middle-aged hypertensive patients (β = -0.34, -0.34, -0.20, all P-values <0.05).Conclusion:Baseline NLR has some predictive value for CAIMT changes after treatment in young and middle-aged hypertensive patients.