Background/Aims: This multicenter study reviewed the clinical features and prognosis according to the primary site of involvement and the treatment modality in patients with B-cell primary intestinal lymphoma (PIL). Methods: Among 125 consecutive patients diagnosed with PIL, 100 patients were analyzed. Results: The median age was 59 years, and the male to female ratio was 1.86:1. Diffuse large B-cell lymphoma (66/100, 66.0%) was the most common histological subtype. The estimated 5-year survival rate (5-YSR) was 48.5%. The 5-YSR was similar regardless of the type of primary treatment (chemotherapy alone vs. surgery/chemotherapy, 50.7 vs. 45.3%, p=0.582). A comparison of the survival according to the primary site of involvement revealed a 5-YSR of 32.5% (p=0.027), 64.3% (reference), 46.5% (p=0.113), and 49.8% (p=0.024) for the small intestine, ileocecal region, large intestine, and multiple sites, respectively. Multivariate analysis, however, revealed a low hemoglobin level, advanced Ann Arbor stage, and aggressive histological type to be independent prognostic factors for shorter survival but not ileocecal region involvement. Conclusions The Ann Arbor stage, hemoglobin level, and histological type were independent prognostic factors for survival, while the primary site of involvement and treatment modality did not affect the prognosis in patients with B-cell PIL.