The 1990 ABC Under-18 Championship was the eleventh edition of the Asian Championship for Junior Men. The tournament took place in Nagoya, Japan from August to 2 September 1990. Top three teams from this competition were qualified for the World Junior Basketball Championship held in Edmonton, Canada from July 26 to August 4 of 1991.
won their first-ever championship after breezing past in the championship match, 82-63. Defending champions , edged out the , 96-93 in the battle for third place.
The top three teams represented Asia to the 1991 FIBA Under-19 World Championship.
Top two teams from each group advance to the final round.