Neoadjuvant multimodality treatment followed by radical surgical resection is a treatment option still under discussion for locally advanced gastric and esophageal cancers. To exclude patients with occult peritoneal carcinomatosis, video-laparoscopy is generally suggested prior to induction of neoadjuvant treatment. We compared the results of standardized diagnostic video-laparoscopy for consecutively treated patients with gastric and esophageal adenocarcinomas. 34 patients with locally advanced adenocarcinomas (cT3/4,Nx,M0) of the stomach (n=17) and gastroesophageal junction type II und III according to Siewert’s classification (n=17) were scheduled for neoadjuvant chemotherapy (cisplatin, leucovorin, 5-FU). 34 patients with adenocarcinomas of the esophagus (cT2-4,Nx,M0) received simultaneous neoadjuvant chemoradiation (36 Gy, cisplatin, 5-FU). Clinical staging in both groups consisted of endoscopy with biopsy, endoscopic ultrasound, and CT chest and abdomen. To exclude occult unsuspected peritoneal carcinomatosis, standardized diagnostic video-laparoscopy with biopsy, peritoneal lavage and conventional cytology was performed prior to neoadjuvant treatment induction. In 5/34 (14,7%) patients with gastric or gastroesophageal junction tumors (Siewert type II and III), peritoneal carcinomatosis was discovered by diagnostic video-laparoscopy and proven by biopsy. These patients were excluded from the neoadjuvant protocol and received definitive chemotherapy. In all patients with biopsy-proven peritoneal carcinomatosis, conventional cytology in peritoneal washings also detected tumor cells. In contrast, none of the 34 patients with adenocarcinomas of the esophagus showed macroscopic peritoneal carcinomatosis and peritoneal washings were all negative by conventional cytology. Diagnostic video-laparoscopy with biopsy and lavage identified peritoneal carcinomatosis in 14.7% of patients with gastric cancers with a consecutive change in the therapeutic concept. In patients with esophageal adenocarcinoms none of them showed occult peritoneal carcinomatosis and therefore no change in the planned treatment was necessary. We therefore stopped using video-laparoscopy in the diagnostic work-up in patients with locally advanced esophageal adenocarcinomas with unsuspected peritoneal carcinomatosis prior to neoadjuvant treatment.