Rochdale: Keith Hill sacked as manager by League One club
Rochdale have sacked manager Keith Hill after six years in charge in his second spell at the League One club
Dale, who are 22nd in the table, have also terminated the contract of his assistant Chris Beech.
Hill, 49, has achieved two of the three promotions in Rochdale's history, most recently from League Two in 2014.
But they have won just once in 12 games since Boxing Day and are now five points adrift of safety in the third tier after four straight defeats.
First team coach Brian Barry Murphy and academy manager Tony Ellis will take training this week ahead of this Saturday's home game against fellow strugglers Shrewsbury Town.
Former Blackburn Rovers, Plymouth Argyle and Dale defender Hill initially spent four-and-a-half years in charge, winning promotion to the third tier for the first time in 2010.
After equalling the club's best-ever league finish - ninth in 2011 - he left to join Barnsley, but returned in January 2013.
"It has been the most difficult decision that the board has had to make," said a club statement. "But it is felt that, due to results on the pitch, a new direction is needed."
"We believe the next five games against opposition in and around us represents a great opportunity to try and retain our League One status, which is why this action has been taken now."
Dale also play three other lower-half sides, 19th-placed Oxford United, 18th-placed Gillingham and 14th-placed Accrington in March.
Former Cardiff City, Rotherham United and Doncaster Rovers left-back Beech, 43, had been at Spotland for 12 years, having joined as youth team manager.
BBC Radio Manchester's Mike Minay
"This has come as a surprise to the staff of the club. His wit, his charm and character will be missed.
"Keith Hill is largely 'Mr Rochdale' - arguably their most successful manager, helping the club to consistently punch above its weight.
"Whenever a manager is under pressure, journalists usually pose questions such as 'do you fear for your job?'. With Keith those questions were never asked. Relegation questions? Yes. His job? Never.
"However, the call has come with the club leaking goals for fun. 31 in 11 matches in 2019, to be precise and with only one win in those games too, plus defeat by relegation rivals Wimbledon 4-3 at home.
"After surviving on the final day of last season, it's hard to see them repeating that success for a second consecutive year.
"A new board appointed in December will also have their own minds about where the club is going, and maybe Keith didn't fit with those plans. Is it the right call? Let's see on 4 May."