A total of 6,394 regional lymph nodes (RLNs) from 319 gastric cancer patients was evaluated histologically for sinus histiocytosis (SH), paracortical lymphocytes (PCL), overall lymphoid cell content (OL), germinal centers (GC), and medullary cord plasma cells (P1). High grade SH, PCL, and OL reactivity was found in cancers confined to the mucosa and submucosa of the stomach wall, and GC and P1 reactivity in cancers that had invaded the subserosa or the serosa of the stomach wall. No stable relationship was found between the RLNs reactivity of patients with and without metastasis to the RLNs. Differences among RLNs reactivities according to location (n1, n2, n3+4) as defined by the Japanese Research Society for Gastric Cancer were evaluated, and n1, the most proximal nodes to the primary cancer, usually had the highest reactivity. As regards the prognostic value of these factors, OL and GC, but not SH, had a significant favorable relation to the 5-year survival rate. In addition, sarcoid-like reaction was evaluated.