AIM: To evaluate discrepancies between biopsy and resected specimens using the Japanese Classification of Gastric Carcinoma(JCGC) and tumor-node-metastasis(TNM) classification.METHODS: A total of 376 consecutive paired samples from biopsy and resected gastric specimens, which were derived from curative gastrectomy for gastric cancer between 2008 and 2011, were retrospectively analyzed.RESULTS:(1) Discrepancies in the histologic type were observed between biopsy and resected specimens; 11.7%(44/376) in the JCGC and 18.1%(68/376) in TNM. In specimens diagnosed as the differentiated type from biopsy specimens, 14.4%(28/195) in the JCGC and 41.1%(67/163) in TNM were finally diagnosed as the undifferentiated type from resected specimens; and(2) the incidence of mixed-type gastric cancer was significantly higher in specimens with discrepancies than in those without in both the JCGC and TNM(both P < 0.0001); 93.2%(41/44) of specimens with discrepancies in the JCGC and 97.1%(66/68) of specimens with discrepancies in TNM were mixed-type gastric cancers. CONCLUSION: Mixed-type gastric cancer was associated with a high incidence of histologic discrepancies between biopsy and resected specimens in both the JCGC and TNM definitions. Care should be taken in deciding treatments based on diagnosis of the histologic typefor mixed-type gastric cancer from biopsy specimens. AIM: To evaluate discrepancies between biopsy and resected specimens using the Japanese Classification of Gastric Carcinoma (JCGC) and tumor-node-metastasis (TNM) classification. METHODS: A total of 376 consecutive paired samples from biopsy and resected gastric specimens, which were derived (1) Discrepancies in the histologic type were observed between biopsy and resected specimens; 11.7% (44/376) in the JCGC and 18.1% (68/376 ) in TNM. In specimens diagnosed as the differentiated type from biopsy specimens, 14.4% (28/195) in the JCGC and 41.1% (67/163) in TNM were finally diagnosed as the undifferentiated type from resected specimens; and (2) the incidence of mixed-type gastric cancer was significantly higher in specimens with discrepancies than those in those without both in the JCGC and TNM (both P <0.0001); 93.2% (41/44) of specimens with discrepancies in the JCGC and 97.1% ( 66/68) of specimen s with discrepancies in TNM were mixed-type gastric cancers. CONCLUSION: Mixed-type gastric cancer was associated with a high incidence of histologic discrepancies between biopsy and resected specimens in both the JCGC and TNM definitions. Care should be taken in deciding treatments on diagnosis of the histologic type for mixed-type gastric cancer from biopsy specimens.