Vollmar was a citizen of Saarland, what came under French protectorate after World War II, and wore the Saarland colours four times, scoring four in these matches. His final Saarland appearance happened under then Saarland coach Helmut Schön less than a month before his first West Germany match under coach Sepp Herberger: On 6 June 1956, Saarland lost 2–3 to the Netherlands in Amsterdam with Vollmar scoring one goal that evening.
With the population of Saarland to join West Germany, via a referendum taken place already in 1955, Vollmar's first of twelve West Germany caps was on 30 June 1956, in Stockholm versus Sweden. He scored his first of three goals against Belgium six months later. Despite the fact a year had passed since his final West Germany match, Heinz Vollmar was part of the West German squad at the 1962 FIFA World Cup.
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