The standard treatment of primary testicular lymphoma (PTL) has not been well established. Our study aimed to evaluate the relationship between the prognostic factors and clinical outcomes of PTL. We retrospectively reviewed the clinical records of 43 PTL patients and included the 39 patients who were diagnosed with primary testicular diffuse large B cell lymphoma (DLBCL) for analysis of prognostic factors and assessment of treatment modalities. Cox regression analysis showed that poor ECOG performance status (PS, a parts per thousand yen2), infiltration of adjacent tissues (spermatic cord, epididymis, or scrotum), and bulky disease (tumor mass, > 9 cm) were independent predictors of worse overall survival (OS) for primary testicular DLBCL. According to these three factors, the patients were divided into two groups. Rituximab was found to significantly prolong progression-free survival (PFS) in the low-risk group (P = 0.044) but not in the high-risk group (P = 0.748). And the combination therapy for CNS prophylaxis significantly prolonged the survival in the high-risk group (P = 0.005 for OS; P = 0.004 for PFS), but not in the low-risk group (P = 0.092 for OS; P = 0.191 for PFS). ECOG performance status, infiltration of adjacent tissues, and bulky disease are practical prognostic factors of survival in patients with primary testicular DLBCL. The addition of rituximab is more important for the patients without the prognostics factors, and the combination CNS prophylaxis is more significant for the patients with the prognostics factors.