A deep infection after total hip arthroplasty is a very severe complication that occurs in about 1~2% of the patients. The major cause of this infection is Staphylococcus aureus in the early stage and Staphylococcus epidermidis in the late stage A nontraumatic gas-forming infection is rare and difficult to diagnose because of its slower clinical course than that of gas gangrene. Therefore, it has a high mortality rate due to delayed treatment. There have been no reports on gas-forming infection by Escherichia coli after total hip arthroplasty. We report here on a patient who was treated by open arthrotomy and the patient expired due to a Escherichia coli, gas-forming infection after undergoing total hip arthroplasty.