Abstract Background Endoscopic submucosal dissection is gaining popularity in the treatment of early gastric cancer. This study aimed to identify clinicopathological factors predictive of lymph node metastasis in patients with the poorly differentiated early gastric cancer to assess the feasibility of using endoscopic submucosal dissection for these cancers. Methods The records of patients with poorly differentiated early gastric cancer who had undergone gastric cancer surgery between January 2002 and December 2009 were reviewed. Associations between clinicopathological factors and the presence of lymph node metastasis were analysed by univariable and multivariable logistic regression analysis. Results Some 1005 patients were included in the analysis. Univariable analysis indicated that lymph node metastasis was associated with sex, ulceration, tumour size, depth of invasion, macroscopic type, lymphatic invasion and venous invasion. Logistic regression revealed that lymph node metastasis was significantly associated with sex, tumour size, depth of tumour invasion and lymphatic involvement. In the group with none of these risk factors (men with mucosal tumour no larger than 2 cm in size, with no lymphatic involvement), lymph node metastasis was present in four (3·2 per cent) of 124 patients. Conclusion In the present study 3·2 per cent of patients who were negative for all identified risk factors had lymph node metastasis. The use of endoscopic submucosal dissection should be considered carefully in the treatment of poorly differentiated early gastric cancer.