In 1964 Roger Gilson won the Grand Prix Général Patton, a junior cycling stage race in Luxembourg, before winning the national junior road race the following year. Gilson continued to have good results, including winning the overall classification at the 1967 Flèche du Sud stage race. One year later he was selected to ride in the road race at the 1968 Mexico City Olympics, finishing 54th. He won the Flèche du Sud again in 1969 before becoming a four-time national road race champion (1972, 1974–76). Gilson rode in two editions of the Tour de France, abandoning the race each time, but he did win the second stage of the 1976 Vuelta a España. He was only 47-years-old when he died from a heart attack after training at a local sports hall.