Prices in the US increased at an annual rate of 8.3% last month, remaining high even as petrol costs eased.
While the annual rate retreated from 8.5% in July, the cost of food, housing and medical care continued to climb, the Labor Department has said.
Economists had hoped to see more widespread easing of the inflationary pressures.
Inflation remains a key issue for Americans, putting pressure on the White House and other policymakers.
