Anticoagulant(heparin, warfarin) or thrombolytic agent(urokinase, tissue plasminogen activator) can be one of the causes of spontaneous ICH. Even though ICH related with anticoagulants and thrombolytic agents represent low incidence and slow progression, the final outcome usually very poor. Recently the use of anticoagulants and thrombolytic agents have been increased for recanalization of cerebral and myocardial infarction. Therefore, the importance of possible ICHs related to these agents need to be reemphesized. The authors analysed 18 patients of ICH related with anticoagulants and thrombolytic agents to evaluate the underlying mechanism, their characters, the factors which influence the formation of ICH and the prognosis. Eighteen cases of ICH related with anticoagulants and thrombolytic agents were analysed through the medical record, operation record and brain CT. In this study, patients in sixth decade showed the highest incidence. The most common primary disease was middle cerebral infarction(67%). Urokinase was most commonly infused for recanalization of cerebral and myocardial infarction. The mean duration between drug administration and hemorrhagic attack was 59 hours(with range from 1 hour to 96 hours). After onset of the hemorrhage, fourteen of eighteen cases revealed prolonged prothrombin time more than 1 1/2 to 2 times of control and nine of fourteen cases revealed prolonged thrombin time more than 1 1/2 to 2 times of cotrol. The mean volume of ICH was 31cc and locations of hemorrhage were lobar(45%), ganglionic(22%), thalamic(22%) and cerebellar(11%) in decreasing orders. Brain CT scans revealed that 12 cases were single hematoma and 6 cases were multiple hematoma. Twelve cases were treated conservatively and six cases were operated with stereotactic surgery(3 cases) and open craniotomy (3 cases). One case with stereotactic surgery and the other case with craniotomy were reoperated because of rebleeding and retained hematoma, respectively. The neurological condition before administration of anticoagulants and thromb-olytic agents was relatively good, but suddenly deteriorated after hemorrhage attack. Almost all cases(94%) prese-nted poor porgnosis as wholly dependent, vegetative and dead at discharge except one case of small cerebellar ICH. In this study, previously existed infarction and anticoagulants itself contributed to the occurrence of intracerebral hemorrhage. The prolonged prothrombin time may be useful predictable value in the formation of ICH. Although we could not find definitive factors to influence the prognosis, the mortality rate of multiple hematoma was much higher than single hematoma. The final outcome of these patients were very poor. Therefore, the choice of agents, dosage and duration of administration should be considered more judicious.