Vilfan made 121 appearances with the senior Yugoslavian national basketball team, between 1977 and 1983, making him the third most capped Slovenian player for Yugoslavia. He played in five major international FIBA tournaments: the 1978 FIBA World Championship, the EuroBasket 1979, the EuroBasket 1981, the 1982 FIBA World Championship, and the EuroBasket 1983. He won one gold and one bronze medal at the FIBA World Cup, and one silver and one bronze at the EuroBasket.