 Having joined the youth ranks of Hamburger SV in 1970, Kargus stepped up to become a Bundesliga goalkeeper for the North Germans from 1971, capturing the starting role in the goal of Hamburg in 1973.He served as the club's first-choice until Hamburg headed for a change on that position in 1980.In his years with Hamburg he graduated into a goalkeeper as promising as reliable, known for his ability to save penalties (which earned him the "Elfmetertöter" nickname).