Lars Grini’s breakthrough as a ski jumper came in 1965, At the national championships on the normal hill he placed third behind the famous jumpers Bjørn Wirkola and Torgeir Brandtzæg. At Holmenkollen the 20-year old from Hadeland impressed by bettering the hill record by two meters, and finished second, only 1.2 points behind the winner Dieter Neuendorf. Two years later he bettered the world ski flying record with 150.0 meters in Oberstdorf. After winning the bronze medal on the large hill at Grenoble in 1968, he won another bronze on the normal hill at the 1970 World Championships in Strbske Pleso. Later the same season he won his first national championship, winning on the normal hill. He repeated this victory in 1973, and won his third and last national title in 1974, this time on the large hill. He ended his career in 1976, and worked for several years as an expert commentator for Norwegian TV, but later became a professional breeder of trotter racehorses at his farm in Gran, Hadeland.