Chromik took eight national titles at long distances: 3000 m steeplechase (1952, 1954, 1956, 1960, 1961, 1962), 5000 m (1953), 10,000 m (1955).
He participated in three European Championships in Athletics in Bern (1954), Stockholm (1958), Belgrade (1962). He also took place in the 1956 Summer Olympics in Melbourne (1956), and the 17th Olympic Games in Rome (1960).
In 1955, Chromik won the 5.000 metres, ahead of Sándor Iharos, József Kovács, Emil Zátopek, and Zdzisław Krzyszkowiak, at the International Youth Festival in Warsaw. In 1955 and 1958, he won the 3000m in the Kusocinski Memorial in Warsaw. In the 1958 European Championship at Stockholm, he won gold medal at the 3000m steeplechase. In 1959, he won a Cross L'Humanité in Paris.
Chromik set the 3000m steeplechase world records with 8:41.2 in Brno (August 1955), 8:40.2 in Budapest (September 1955), and 8:32.0 in Warsaw (August 1958).
