Romanidis was also a member of the senior men's Greek national team. He played with Greece at the 1983 EuroBasket, the 1984 FIBA European Olympic Qualifying Tournament, and the 1986 FIBA World Championship. He was also a member of Greece's team that won the gold medal at 1987 EuroBasket. He played in 82 games with Greece, averaging 4.4 points per game.