Marjolin's ulcer is defined as a tumor arising from a chronic wound, scar or chronic inflammation. Commonly, it is histologically diagnosed as a squamous cell carcinoma or a basocellular carcinoma. Its management includes its excisioning including a sufficient circumferential rim and histological examination of the sentinel lymphnode. The authors present a case review of a 51-year-old male with a history of a sacral decubitus, treated for over 40 years. The patient was hospitalized to cover the defect with a skin flap. During the hospitalization, histological examinations of his inguinal lymphnodes and subsequent wound granulations were performed with an identical finding of a squamous cell carcinoma. Based on the findings, the Marjolin's ulcer was diagnosed. The patient underwent the first series of chemotherapy. However, the patient's condition deteriotated. He exited 24 days following establishment of the diagnosis. The aim of this study is to highlight one of the most dangerous complications of chronic wounds. Marjolin's ulcer is a diagnosis, which must be considered in any chronic wound of any etiology, persisting for over 3 months.