Henson will have a scan to asses the extent of the injury when he and his team-mates arrive home from Dublin following the 43-20 reverse at the hands of the former European Champions.
The news is a major blow to the ex-Ospreys centre who is less than a month into his return from a self-imposed exile following a string of injury setbacks.
Henson had made it clear he hoped to challenge for a place in the Wales squad for next month's Six Nations - a target that was made even more realistic following fellow centre Andrew Bishop's recent ankle injury.
That goal now appears to be in serious danger, although neither Henson or his club have made any further comment on the seriousness of Saturday's setback.
Henson only appeared as a replacement in the Irish capital, coming on after 35 minutes, but he was forced to depart just past the hour mark as Leinster ran riot at the RDS.
The news is a further blow to Wales coach Warren Gatland who lost Lions prop Gethin Jenkins and Blues scrum-half Richie Rees to injury and suspension earlier this week.