Despite the use of potent antibiotics and intensive supportive care, the mortality among patients with sepsis and Gram-negative bacteremia remains high. In recent years, endotoxin adsorption therapy (PMX-DHP, polymyxin-direct hemoperfusion) has been widely used in Japan to remove endotoxin, a causative agent of sepsis. In septic patients whose clinical condition may change at any moment, the decision of when to perform blood purification in addition to conventional intensive care is a critical factor in the therapeutic strategy and prognosis. In the present study, we investigated the effect over time of PMX-DHP in sepsis. The subjects were 16 patients with systemic inflammatory response syndrome (SIRS) who required surgical treatment including a surgical operation and drainage. The following six parameters were compared between the first and second PMX-DHP: mean blood pressure and time-restricted urine at four time points - at baseline and at 6, 24 and 72 h after PMX-DHP; and white blood cell count, platelet count, base excess and Septic Severity Score (SSS) at 24 and 72 h after PMX-DHP. Mean blood pressure improved over time up to 24 h after both the first and second PMX-DHP. Time-restricted urine volume improved only at 6 h after the first PMX-DHP. White blood cell count improved over time up to 24 h after both the first and second PMX-DHP. The SSS improved at all time points studied except for 3 days after the second PMX-DHP. We conclude that PMX-DHP is expected to have important implications in terms of (i) correction of clinical conditions (by severity assessment); (ii) improvement of hemodynamics; (iii) possible anti-inflammatory effect; and (iv) possible improvement of oxygen metabolism in tissues.