We retrospectively investigated pathological types, clinical backgrounds, treatments and prognoses in 726 adult patients with newly diagnosed malignant lymphoma in Gunma Prefecture. They consisted of 679 patients with non-Hodgkin lymphoma (B-cell type, 603; T- and NK-cell type, 76) of which 376 patients had diffuse large B-cell lymphoma (DLBCL) and 47 patients with Hodgkin lymphoma. When comparing the prognosis of DLBCL between patients receiving rituximab (R-CHOP group; n=212) and not using rituximab (CHOP group; n=126), both 3-year overall survival (73.5% vs 61.7%, p=0.010) and 3-year progression-free survival (65.1% vs 45.8%, p<0.001) were statistically better in the R-CHOP group compared to the CHOP group. Our results suggest that more than half of patients were DLBCL and the rituximab-containing regimen results in an improved prognosis for DLBCL patients.