Background. Currently, there is a steady trend towards an increase in the incidence of both synchronous and metachronous multiple primary malignant tumors (MPMT). However, metachronous polyneoplasia of the pancreatobiliary tract is relatively rare, and there have been very few reports on successful treatment of this malignancy. Case presentation. In September 2014, the patient K. was diagnosed with adenocarcinoma of the ampulla of Vater (T2N0M0, stage Ib) and underwent gastropancreatoduodenal resection with the creation of pancreatic-gastric anastomosis at the Abdominal Department of Cancer Research Institute of Tomsk National Research Medical Center. There were no complications in the postoperative period. At a 6.5-year followup, no evidence of disease progression was found. In April 2021, a follow-up examination conducted at the Cancer Research Institute revealed a large lesion on the distal part of the pancreatic stump with no clinically significant manifestations. Diagnosis of MPMT was confirmed by transgastric endoscopic ultrasound-guided biopsy. Histological and immunohistochemical examinations revealed undifferentiated ductal carcinoma of the pancreas. Considering the metachronous tumor localization, pancreatic stump extirpation with resection of the posterior wall of the stomach and splenectomy was performed. No complications occurred in the postoperative period. The patient received replacement therapy for exocrine pancreatic insufficiency and individual correction of carbohydrate metabolism. At a 15-month follow-up, liver metastases were detected, and palliative chemotherapy was administered. The patient died 6 months later due to disease progression. The survival time was 99 months after the first surgery and 21 months after the second surgery. Conclusion. We report a rare case of metachronous cancers of the ampulla of Vater and pancreatic stump developed with an interval of 6.5 years. The patient underwent successful curative resections consecutively. The overall survival time from the date of diagnosis was 99 months.