Background: For patients with locally advanced esophageal carcinoma undergoing neoadjuvant chemoradiation/chemotherapy followed by surgical resection, complete pathological response is associated with favorable overall survival(OS). PET scan is considered an important modality in staging of esophageal cancers. Off late, its use in assessing the response of neoadjuvant therapy is coming up. Whether the radiological response shown in PET scan before and after neoadjuvant chemoradiation or chemotherapy actually transforms into histopathological response and whether it would act as a predictor of overall survival is yet to be established. Aim: To evaluate the role of positron emission tomography (FDGPET) in assessing the response to neoadjuvant chemoradiation/ chemotherapy and comparing it with histopathological response and its relation to overall prognosis. Methods: Retrospective data from October 2011 to December 2016 of operable patients with locally advanced carcinoma esophagus or gastroesophageal junction cancers was analyzed. All patients underwent FDG PET for initial staging and 4-6 weeks after completion of neoadjuvant chemoradiation or chemotherapy followed by definitive surgery. Results: The study included 96 patients. Most tumors were squamous cell carcinoma (62%) and stage T3(75%). All patients received neoadjuvant treatment (68 chemoradiation and 28 neoadjuvant chemotherapy). Post neoadjuvant treatment, PET scan showed complete metabolic response in 31 patients (32%), good response in 61 patients (63%) and stable disease in 4 patients (5%). 28 patients (29%) showed complete pathological response, 44 (46%) showed partial response and 24(25%) showed no response at all. PET CT response did not corroborate with the final histopathological response (p=0.235). Overall survival of patients showing complete metabolic response is 512.87 days, 526.7 days for patients with good response. 2 out of 3 patients with stable disease have expired. Conclusion: FDG PET response to neoadjuvant treatment in carcinoma esophagus and GE junction does not effectively correlate with the final histopathological response and to overall survival. Surgical decision should not be based on PET CT response and should be offered to all the patients irrespective of metabolic response. [ABSTRACT FROM AUTHOR]