We studied the influence of circumferential resection margin (CRM) involvement on survival in patients with malignancies of the distal esophagus and gastroesophageal junction. One hundred ten consecutive patients undergoing a laparoscopic or open transhiatal esophagectomy for malignancy of the distal 5 cm of the esophagus, or a Siewert I gastroesophageal junction tumor were analyzed, retrospectively. Only patients with potentially resectable tumors were included. CRM status was defined as clear or involved (microscopic tumor within 1 mm of the resection margin). Statistical analysis was done by means of univariate and multivariate analysis using the Kaplan-Meier method and Cox proportional hazard model. One hundred ten patients were analyzed. Sixty patients underwent open transhiatal esophagectomy, and 50 patients underwent laparoscopic transhiatal esophagectomy. There were 6 (5%) T(1), 18 (16%) T(2), and 86 (89%) T(3) tumors. CRM was clear in 68 (62%) patients and involved in 42 (38%) patients. Median survival in these groups was 50 vs. 20 months (P = 0.000). Since CRM involvement was only seen in T(3) tumors, this group was analyzed in detail. Median survival in the T(3)CRM(-) and T(3)CRM(+) group was 33 vs. 19 months (P = 0.004). For T(3)N(0) tumors, median survival in CRM(-) and CRM(+) was 40 and 22 months, respectively (P = 0.036). Median survival for T(3)N(1) tumors in CRM(-) and CRM(+) was 22 and 13 months, respectively (P = 0.049). Involvement of the circumferential resection margin was found to be an independent prognostic factor on survival in our study. It predicts a poor prognosis in patients with potentially resectable malignancies of the distal 5 cm of the esophagus and Siewert I adenocarcinomas of the gastro esophageal junction.