Background: Red cell distribution (RDW) has been suggested to be associated with cardiovascular mortality and mortality. However, few studies have yet investigated the possible association between RDW and early-stage renal function damage in patients with primary hypertension without receiving drug treatment. Accordingly, the aim of the present study was to evaluate early-stage renal function status in patients with RDW levels. Results: The study included 513 primary hypertension patients (319 men and 194 women) without receiving drug treatment. Significant positive correlation was observed between albumin-to-creatinine ratio (ACR) and RDW in hypertensive patients (r = 0.531, P< 0.001). In multivariate line regression analysis, night-time SBP (B = 0.042, P< 0.001), ACR (B = 0.005, P< 0.001), and uric acid (B = 0.001, P = 0.022) were positive predictors of RDW independent of age, sex, hemoglobin, and other indexes, whereas daytime SBP (B = -0.019, P< 0.001) was inversely associated with RDW. The receiver operating characteristics curves (ROC) explored the relationship between renal function status and RDW, estimated glomerular filtration rate (eGFR), serum creatinine, and high-sensitivity C-reactive protein. The area under the curve was 0.81 (95% CI: 0.77-0.85; P< 0.001), 0.45 (95% CI: 0.39-0.50; P = 0.049), 0.49 (95% CI: 0.430.54; P = 0.583), and 0.49 (95% CI: 0.44-0.55; P = 0.811), respectively. Using a cutoff point of 12.8, the RDW predicted renal function status (ACR) with a sensitivity of 76% and a specificity of 70%. Conclusion: RDW, as an easy and quick measurable index, can predict early-stage renal function damage in essential hypertensive patients without receiving drug treatment.