Genomic alterations and protein expression levels have been established as prognostic factors for survival in patients with diffuse large B-cell lymphoma (DLBCL). In particular, double-hit DLBCL (DHL), which exhibits translocations in MYC and BCL2 and/or BCL6, is known to be associated with a poor prognosis. However, the clinical significance of gene alterations and protein expression levels for MYC, B-cell lymphoma (BCL)2, and BCL6 are unclear. In this study, we analyzed 61 adult patients diagnosed with DLBCL without DHL, who were treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone, or similar regimens. There were no differences in the distribution of MYC expression rates among the different MYC gene statuses. In log-rank tests, MYC translocation was a prognostic factor for overall survival (OS; P = 0.011), whereas BCL2 and BCL6 translocation were not prognostic indicators (P = 0.999 and P = 0.925, respectively). Although the expression levels of MYC and BCL6 were not significantly associated with OS, the expression of BCL2 was a prognostic factor for OS (P = 0.027). Furthermore, copy number gains in the MYC, BCL2, and BCL6 genes did not affect OS. MYC translocation (hazard ratio, 4.769; range, 1.518-14.98; P = 0.007) and BCL2 protein expression (hazard ratio, 3.072; range, 1.002-9.413; P = 0.049) were independent prognostic factors for survival in multivariate analyses. In conclusion, MYC translocation and BCL2 expression may need to be investigated at the initial diagnosis to predict prognosis in patients with DLBCL.