The present study describes the diagnosis and treatment of hyperfibrinolysis following surgery in a 25-year-old female patient. An examination revealed that the left kidney had been affected by severe hydronephrosis for two weeks prior to hospitalization. The diagnosis of a parapelvic cyst was obtained by preoperative intravenous pyelogram (IVP), computed tomography (CT) and upper left urinary tract retrograde pyelography. Unroofing of the left parapelvic cyst was performed by open surgery. The patient exhibited symptoms of shock 48 h later, and her hemoglobin (Hb) levels dropped to only 62.2 g/l. To treat this, 400 ml erythrocyte suspension transfusion was administered 3 times every other day. The patient’s Hb levels remained between 50 and 60 g/l. The D-dimer assay index rose from 0.3 to 16 mg/l and the fibrin degradation product (FDP) levels progressively increased following the hemorrhage, while the platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen (Fg) index were all within normal levels. p-Aminomethylbenzoic acid (PAMBA; 0.5 g) was administered to the patient every day, and as a consequence the Hb levels rose steadily from the next day onwards. After a one week course of PAMBA treatment, the patient’s condition became stable. Blood coagulation and fibrinolytic function measurements were all within the normal ranges in the three months following the surgery. Delayed hemorrhage following surgery should be considered as a possible cause of hyperfibrinolysis. Monitoring FDP and D-dimer levels may aid a rapid and clear diagnosis. Anti-fibrinolytic therapy, such as PAMBA treatment, is safe and effective for use against the type of hemorrhage caused by hyperfibrinolysis.