Background The aim of this study was to determine the added value of portal or superior mesenteric vein (PV/SMV) resection during pancreatoduodenectomy for pancreatic head carcinoma. Methods A multicentre observational study was conducted in patients with pancreatic head carcinoma who underwent pancreatoduodenectomy in seven Japanese hospitals between 2001 and 2012. Clinicopathological factors were compared between patients who did and did not undergo PV/SMV resection. Those with an impact on survival were identified by univariable and multivariable analysis. Results Of the 937 patients who underwent pancreatoduodenectomy, 435 (46·4 per cent) had PV/SMV resection, whereas the remaining 502 (53·6 per cent) did not. Some 71·5 and 63·9 per cent of patients with and without PV/SMV resection respectively had lymph node‐positive disease. Patients who underwent PV/SMV resection had more advanced tumours. Perioperative mortality and morbidity rates did not differ between the two groups. Multivariable analysis revealed that PV/SMV resection was not an independent prognostic factor for overall survival (P = 0·268). Among the 435 patients in whom the PV/SMV was resected, borderline resectable tumours with arterial abutment (P = 0·021) and absence of adjuvant chemotherapy (P < 0·001) were independent predictors of poor survival in multivariable analysis. Patients with resectable or borderline resectable tumours with PV/SMV involvement had a median survival time with additional adjuvant chemotherapy of 43·7 and 29·7 months respectively. Median survival time in patients with borderline resectable tumours with arterial abutment was 18·6 months despite adjuvant chemotherapy. Conclusion Pancreatoduodenectomy with PV/SMV resection and adjuvant chemotherapy in patients with pancreatic head carcinoma may provide good survival without increased mortality and morbidity. Potential role for adjuvant chemotherapy