Doripenem (DRPM) is one of the carbapenems which has a broad-spectrum and strong activity against Pseudomonas aeruginosa. This observational study was conducted between April 2006 and March 2007 in Japan to evaluate the efficacy and safety of DRPM 0.5 g three times a day for sepsis with neutropenia in patients with hematologic diseases. One hundred-nineteen patients were enrolled from 34 medical institutes, comprising 117 patients for safety evaluation and 104 for efficacy evaluation. Monotherapy of DRPM 0.5 g three times a day (DRPM monotherapy) was evaluated in 73 patients. The response rates of DRPM monotherapy at 72 hours and at Day 7 were 31.5% (23/73) and 67.1% (49/73), respectively. The incidence of adverse reactions including abnormal changes in laboratory values was 23.1%, and hepatic toxicity was most common. All of these adverse events were judged by the investigators as non-serious and tolerable. These results suggest that DRPM is useful for sepsis with neutropenia, though further study may be warranted.