Abstract: Objective To explore the expression of MYC in diffuse large B-cell lymphoma （DLBCL） and its relationship with the prognosis of DLBCL. Methods The clinical data of 220 patients with DLBCL admitted to Guangxi Medical University Cancer Hospital from February 2011 to August 2018 were retrospectively analyzed. The expression of MYC protein was detected by immunohistochemistry，and to analyze the correlations of MYC protein with clinical pathological characteristics and prognosis. Datasets containing the survival data and gene expression data about DLBCL were collected by searching Gene Expression Omnibus（GEO） to analyze the expression of MYC gene and its relationship with prognosis. Results The positive rate of MYC protein expression in 220 cases of DLBCL tissues was 18.64%. The overall survival（OS） and progress-free survival （PFS） of patients with positive MYC protein expression were significantly shorter than those with negative MYC protein expression（P<0.001）. Subgroup analysis indicated that in germinal center B-cell-like（GCB） subtype，the OS of patients with positive MYC protein expression were obviously shorter than that of patients with negative MYC protein expression，showing a statistically significant difference （P<0.001）. In non-GCB subtype，the OS and PFS of patients with positive MYC protein expression were shorter than those of patients with negative MYC protein expression，showing statistically significant differences（P<0.001）. The result of  Cox proportional hazard regression model analysis suggested that MYC protein expression was an independent risk factor for the prognosis of DLBCL patients（P<0.001）. GSE10846 dataset in GEO was analyzed，and the result con-firmed that the OS of patients with high MYC gene expression was evidently shortened （P<0.01）. Conclusion Patients with high MYC expression have a poor prognosis.

Key words: Diffuse large B-cell lymphoma, MYC, Immunohistochemistry, Immunological subtype, Prognosis