Folke Alnevik took up track and field athletics in school, but World War II delayed the start of his international career until after the conflict. He captured his first major international medal in 1946, a bronze in the 4x400 metres relay at the European Championships, alongside the non-Olympians Stig Lindgård, Sven-Erik Nolinge, and Tore Sten. His greatest moment, however, came at the 1948 London Olympics, where he won a bronze medal in the same event, this time with Kurt Lundquist, Lars-Erik Wolfbrandt, and Rune Larsson. He was also eliminated in the quarterfinals of the 400 metres at those Games. He retired from active competition by the end of the decade, but later became involved in sports administration, particularly the promotion of golf in the Gävle region. By career he served in the military and worked with the United Nations.
Personal Best: 400 – 48.1 (1947).