Gustaf Jansson was the best Swedish marathon runner in the early 1950s. He won bronze at the 1952 Olympics and finished fourth at the 1954 European Championships. In 1950 and 1954 he was also second at the Košice Peace Marathon, the oldest marathon in Europe, and second oldest in the world after the Boston Marathon. Jansson was second at the 1951 Tampere marathon, third at the 1954 Karlstad Marathon, fourth at the 1955 København Marathon, fifth at the 1954 Bern Marathon, and sixth at the 1955 Boston Marathon (with a personal best of 2-21:40). Domestically Jansson won seven Swedish titles – in 1950-53 in the 25,000 metres and in 1951-53 in the marathon.
Personal Best: Mar – 2-21:40 (1955).