Zurich has announced it will not be renewing its sponsorship of the Premiership when the current deal expires at the end of next season. The insurance giant, which took over as title sponsor in 2000, said the decision followed an "internal review of brand strategy".
Premier Rugby, which runs the Premiership, now has 18 months to find a new sponsor.
Its efforts will be boosted by the unprecedented popularity of the game.
Attendances for club rugby are up 15% and Premier Rugby recently signed a new lucrative television deal.
Zurich announced in April they had struck a deal to be the Lions' official shirt sponsor on next year's eagerly awaited tour of New Zealand.