Subject operating characteristic curve (ROC) analysis suggested that serum lincRNA-p21 could differentiate chronic hepatitis B patients with liver fibrosis from healthy controls, specifically the area under the ROC curve (AUC) was 0.854 [0.805–0.894], with a sensitivity and specificity of 100 and 70%, respectively, at a critical value of 3.65. The gene discussed is CDKN1A; the disease is chronic hepatitis B virus infection.