Exit polls broadcast by German media show Ms Merkel’s conservative Christian Democrats (CDU) came first with 28 percent of the vote – a stark difference to the 38.3 percent it won in 2013.
The Chancellor’s coalition allies, the SPD, won 20 percent – down from 30.7 percent from 2013 election.
Meanwhile, opposition parties appear to have made huge gains.
The ecologist Greens narrowly missed out on second place with 19.5 percent of the vote, according to the exit poll.
And the right-wing AfD looks set to enter the Hesse regional government for the first time after securing 12 percent of the vote.
This is a breaking story. More to follow…