Heartland Express said its third-quarter profit fell 19.3% from a year ago.
Net income fell to $12.4 million, or 15 cents per share, from $15.4 million, or 17 cents, a year ago.
Revenue rose 1.9% to $135 million, the truckload carrier said Thursday.
Heartland said it was continuing to upgrade its trailer fleet and that it took delivery of 496 new Wabash trailers in the third quarter.
By the end of the 2012, its entire trailer fleet will be 2007 models or newer, Heartland said.
Heartland Express is ranked No. 47 on the Transport Topics 100 listing of U.S. and Canadian for-hire trucking companies.