In 1959, he was cast as the young rancher Slim Sherman, the lead role on "Laramie" (1959–1963) with Robert Fuller, Hoagy Carmichael, Robert L. Crawford, Jr., Stuart Randall, and later Spring Byington and Dennis Holmes. From their stint on "Laramie", Smith and Robert Fuller developed a lifelong friendship, until Smith's own death in early 1995. On the first episode of the second season "Queen of Diamonds," he introduced Julie London to Fuller, who also developed a lifelong friendship with Smith's co-star, until London's own death, late in 2000.