Lamar Smith ran for a vacant seat in the U.S. House in 1986, and he was elected with 61 percent of the vote. He was re-elected in 1988 without major party opposition, and in 1990 he defeated Democrat Kirby Roberts with 75 percent of the vote. He won re-election in 1992 with 75 percent of the vote, defeating Democrat James Gaddy.
He faced no major party opposition in 1994 or 1998.
In 1996, he was re-elected with 76 percent of the vote against Democrat Gordon Wharton. Smith won 76 percent of the vote in defeating Democrat Jim Green in 2000.
In 2002, he won re-election with 73 percent of the vote.
He faced token opposition in the 2004 general election.
Before his election to Congress, Smith was elected to the Texas House in 1981 and to the Bexar County Commissioners Court in 1982 He was re-elected in 1984.