Phlegmasia cerulea dolens is an extreme form of deep venous thrombosis with a proximal localization of the blockage, most frequently in the ileofemoral area. Symptoms are graded as follows: swelling of the entire extremity, pain, and cyanosis. This form of the disease is rare, occurring most frequently in the terminal stage of malignancies. Diagnosis of phlegmasia usually causes no problems because the proper diagnosis is usually revealed during clinical examination and confirmed by imaging techniques. The authors present a case report of phlegmasia cerulean dolens and discuss the options for treatment.