The effects of direct hemoperfusion with polymyxin B immobilized fiber (PMX) treatment for septic shock have been recently reported. However, little evidence of a true benefit on clinical outcomes, including mortality, is available. Herein, we report three cases of intra-abdominal infection associated with refractory septic shock Case 1 was Escherichia coli peritonitis after a colectomy. PMX treatment improved the hemodynamic parameters and lactic acid levels of the patient. In case 2, secondary peritonitis was associated with septic or cardiogenic shock. Septic cardiomyopathy was assumed to be the cause of shock. 24 hours after the use of PMX, cardiac contractility assessed by echocardiography returned to baseline. In case 3, a patient with Burkitt's lymphoma and neutropenia was found to be gastroenteritis and Klebsiella pneumoniae bacteremia. Intravenous meropenem was administered for 3 days. Hemodynamic parameters improve after the twice use of PMXOverall, the change of serial sequential organ failure assessment score (SOFA) was more significant in surgical cases as compared to the medical case at 72 hours after PMX administration. All patients were discharged from the hospital. In addition to early resuscitation efforts and infection source control, PMX treatment may be beneficial to patients with refractory intra-abdominal infection associated with septic shock.