Leitner, who started for SC Oberstdorf, contested his first international jumping competition with the Four Hills Tournament in 1975/76 . However, on his first tour he was unsuccessful. For the Four Hills Tournament 1977/78 he was able to jump into the top ten for the first time in Oberstdorf and Garmisch-Partenkirchen with a 5th and an 8th place. But these were his highest placements in the tour for two years. However, he recorded a success as the overall winner of the ski flying days from March 3rd to 5th, 1978 on the Kulm in Tauplitz / Bad Mitterndorf , where he no longer gave up the overall lead thanks to his victory on the first day.
After the Olympic Games, he always achieved a place within the World Cup points in the remaining jumping of the 1979/80 World Cup season . In Lahti and Falun he reached 6th place each and in his last World Cup competition in Štrbské Pleso he reached his first and only podium in his career with second place. With the 24th place in the overall World Cup ranking he ended his active ski jumping career.