The 23-year-old striker who has scored 17 times this season is believed to have suffered a broken tibia, following a collision with Ipswich keeper Richard Wright nine days ago.
An initial scan on the Carrot-topped assassin`s leg suggested that there was no serious damage done, but later x-rays revealed the full extent of the problem.
The news comes as a severe blow to Albion boss Gary Megson, who has engineered an improvement in form since arriving at the Black Country club including taking points off promotion-chasing Ipswich and Barnsley in the last two games.
Despite this his side are still precariously placed, just two points clear of third-bottom Walsall.
Hughes` injury puts the emphasis firmly on West Brom legend Bob Taylor to shoot the goals to keep them in the First Division.
Taylor scored his first goal in his second spell at the club at Barnsley last weekend, his 100th league goal for The Baggies, and he will be required to keep on hitting the target if Albion are to stay up.
