Phlegmasia cerulea dolens (phlebitis, cyanosis, pain) is a rare severe form of deep venous thrombosis, caused by obstruction of the vein flow of the lower limb (usually) with severe cyanosis and circulatory compromise which affects collateral vessels, unlike Phlegmasia alba dolens not compromise collateral vessels. It is characterized by sudden onset of pain, because an increase of the venous pressure, that can lead to pulselessness and gangrene. Is unfrequently in daily medical practice, so the diagnosis is important to avoid gangrene. We present three cases of patients attended with this disease. Diagnosis was confirmed by clinic and imaging; we present the evolution and medical treatment that was performed.