Craniotomy　and　membranectomy　are　widely　accepted　for　the　treatment　of　organized　chronic　subdural　hematoma　(CSDH);　however,　to　our　knowledge,　the　efficacy　of　burr　hole　irrigation　and　drainage　with　urokinase　(UK)　for　organized　CSDH　has　not　been　previously　investigated.　This　case　report　describes　4　cases　of　organized　CSDH,　which　were　cured　by　UK　injection　into　the　hematoma　cavity　after　one　burr　hole　surgery.　All　patients　were　male　(aged　55,　55,　58,　and　76　years).　One　patient　underwent　an　initial　single　burr　hole　craniotomy　with　a　partial　membranectomy　and　a　burr　hole　13　and　21　days　after　the　first　procedure.　UK　was　subsequently　injected　into　the　hematoma　cavity.　One　patient　underwent　burr　hole　surgery　twice　in　10　days,　and　UK　was　injected　into　the　hematoma　cavity　after　the　second　burr　hole　operation.　Two　patients　underwent　one　burr　hole　operation　and　UK　injection　into　the　hematoma　cavity　following　surgery.　Organized　hematoma　drainage　was　satisfactory　following　UK　administration.　All　patients　exhibited　full　recovery　without　recurrence　of　the　CSDH.　There　was　no　morbidity　or　mortality　associated　with　UK　injection.　After　a　follow-up　period　of　two　months,　a　computed　tomography　(CT)　scan　indicated　complete　resolution　of　the　hematoma　in　all　4　cases.　These　findings　provide　preliminary　evidence　that　UK　treatment　after　CSDH　is　a　beneficial,　safe,　and　effective　treatment.