Although numerous studies about primary extranodal diffuse large B cell lymphoma (DLBCL) were reported sporadically, the literature of clinical value of immunophenotype and bulky diameter in rituximab era is limited. Ninety-six patients with primary extranodal DLBCL receiving R-CHOP therapy were analyzed to evaluate whether immunophenotype and size of bulky disease are significantly important. The International Prognostic Index was still an important prognostic factor for progression-free survival (PFS) and overall survival (OS; p = 0.003, p = 0.027). Difference of survival between germinal center (GC) type and non-GC type was not different (PFS: p = 0.192; OS: p = 0.197). In two separated groups according to extranodal maximum tumor diameter (EN-MTD) 7.5 cm as cutoff value for survival, the group of EN-MTD > or =7.5 cm had lower PFS and OS than <7.5 cm (PFS: p = 0.001; OS: p = 0.008). In four divided subgroups according to EN-MTD combined with immunophenotype, the subgroup of non-GC type with EN-MTD > or = 7.5 cm had lower PFS and OS compared with the other subgroups (PFS: p < 0.001; OS: p = 0.008). Multivariate analysis revealed that non-GC with EN-MTD > or = 7.5 cm was an independent prognostic parameter (PFS: HR = 5.407, 95%CI = 2.378-12.294, p < 0.001; OS: HR = 4.136, 95%CI = 1.721-9.941, p = 0.002). Bulky primary extranodal DLBCL would be associated with unfavorable outcome especially in non-GC type.