Introduction: Hyperfibrinolysis induced by factor XIII deficiency (FXIIID) is extremely rare, and patients with no manifestations of active bleeding can easily and frequently be neglected in clinical practice, leading to a missed diagnosis. Herein, we report a rare case of idiopathic FXIIID with secondary hyperfibrinolysis. Patient concerns: A 69-year-old man presented with ecchymosis of the right arm and chest wall. Diagnosis: Considering the clinical picture, coagulation function test results, and FXIII activity, the patient was finally diagnosed with hyperfibrinolysis secondary to acquired factor XIII deficiency. Interventions: The patient was treated with fresh frozen plasma, aminomethylbenzoic acid, a prothrombin complex, etamsylate, dexamethasone, and cryoprecipitate. Outcomes: The patient improved and was discharged after factor replacement therapy, and no further bleeding was reported 1 month after discharge. Conclusion: This case report illustrates that the complications of Factor XIII deficiency may include hyperfibrinolysis. Since timely diagnosis of FXIIID is challenging, detailed coagulation factor examinations are needed for definitive diagnosis. It has been suggested that gene testing and antibody testing can help in diagnosis. If ideal treatment is not available, alternative treatment should be provided to reduce bleeding.