"Following the defeats against our direct relegation rivals VfB Stuttgart and St Pauli, we have to rethink our situation," sporting director Max Eberl said in a statement. "It was a difficult decision for us."
Gladbach, who have lost three of their last four games and suffered a 3-1 defeat by St Pauli on Saturday, are bottom on 16 points from 22 games. They also have the worst defence in the league having conceded 56 goals.
Former Gladbach player and assistant coach Frontzeck, who had extended his contract last summer to 2013, had taken over in 2009 after previously coaching Arminia Bielefeld.
"We would have liked to have met our goals together with Michael Frontzeck but following the latest results we decided to change our coach," said club vice president Rainer Bonhof.
