In 1947, Grosics made his debut with the Hungary national football team. With the rather short Grosics in the goal, the team started an unbeaten streak in 1948 that would last until the 1954 FIFA World Cup. In 1949, he attempted to defect and was caught. He was charged with espionage and treason by the secret service and placed under house arrest. The charges were eventually dropped due to lack of evidence, but Grosics was banned from the national team for two years. However, after a year he returned to the national team. He also joined the Budapest Honvéd FC in 1950.