The Prototheca species are achlorophyllic algae and they are recognized pathogens in animals. They have been reported to cause infections in humans; the majority of the infected patients are immunocompromised. Organ transplant recipients are at risk of infection caused by such unusual organisms. Here we present a highly atypical case report of Prototheca mimicking a cecum tumor in a kidney recipient 7 years after the transplantation. Three years before this Prototheca infection, after a native nephrectomy, the patient underwent a complicated duodeno-jejunal reconstruction with feeding catheter jejunostomy. Imaging studies indicated a tumor-like space occupying lesion in the cecum. The patient was treated successfully with colon resection. Detailed histology excluded malignancy and proved Prototheca wickerhamii. The pathogenesis and many biological aspects of human protothecosis are unclear. Usually, treatment involves both medical and surgical approaches. The surgical treatment should be complete excision. The literature suggests an extremely high mortality rate, and therefore we advocate aggressive surgery in organ transplant recipients. This case is the first report of a successfully treated gastrointestinal manifestation of protothecosis in an organ transplant recipient.