BackgroundDisseminated intravascular coagulation (DIC) has been reported in various solid malignancies and is a common coagulation‐related complication in prostate cancer. However, DIC has been rarely reported as the initial presentation of prostate cancer. Herein, we reported a patient referring with subdural hemorrhage (SDH) and DIC with an unexplained cause who was later diagnosed with prostate cancer.Case PresentationWe presented a 68‐year‐old man who was referred to the hospital with a gradual deterioration of consciousness, dyspnea, and edema in the genitalia and lower limbs. His primary laboratory tests showed elevated prothrombin time (PT) and partial thromboplastin time (PTT) and a decreased fibrinogen level of 47 mg/dL [200–400 mg/dL]. The DIC score was 7, which was suggestive of DIC. Moreover, cranial imaging showed SDH. Further work‐up revealed elevated prostate‐specific antigen and prostate enlargement with a mass effect on the bladder with a bone lesion, which was suggestive of metastatic prostate cancer.ConclusionThis report highlights DIC as a possible initial presentation of an underlying malignancy, as well as the importance of treatment of underlying disease in the management of DIC. A comprehensive and systematic work‐up is essential for early diagnosis in patients with DIC to avoid further complications and mortality.