Purpose Pancreaticoduodenectomy (Whipple procedure) is the gold standard surgical procedure for resectable head of pancreas masses. With increasing rates of upper gastrointestinal surgery for weight loss and other indications, an increasing proportion of Whipple procedures will be undertaken on patients with altered anatomy. There is limited literature regarding this, particularly in the setting of a prior Puestow procedure (longitudinal pancreaticojejunostomy). We present one such case, with accompanying diagrammatic representations. Methodology We present a case of a 57-year-old female with prior surgical history including a one-anastomosis gastric bypass as well as a Puestow procedure for chronic pancreatitis. They then presented with back pain, jaundice, and an obstructing head of pancreas mass on CT. The biliary obstruction was initially managed with percutaneous transhepatic cholangiography (PTC) drain insertion while the mass was further evaluated. MRCP and PET scans demonstrated an isolated head of pancreas mass that was highly suspicious for malignancy. Results The patient underwent an open Whipple procedure. After adhesiolysis and mobilisation, the pancreatic head was transected via a stapler leaving the original Puestow pancreaticojejunostomy intact. The jejunum was divided just proximal to the site of the pancreaticojejunostomy with a hepaticojejunostomy created distal to this. The specimen was delivered alongside the remnant stomach from the prior gastric bypass. The patient recovered well and was discharged 9 days later. Conclusion Whipple procedure is a feasible operation in patients with altered anatomy from a Puestow procedure, however it requires careful consideration of the anatomy.