In 1982 and 1983, Marčiulionis played sparingly with the Soviet juniors. He won a gold medal at the 1982 FIBA Europe Under-18 Championship, and a silver medal at the 1983 FIBA Under-19 World Cup, in Spain. Marčiulionis was frequently the last man cut from the senior Soviet Union national basketball team training camps, until he finally got his chance with the senior team in 1987, having a breakout performance, while winning a silver medal at the EuroBasket 1987. Marčiulionis would also be one of the standout players, as the Soviets won the gold medal at the 1988 Summer Olympics.