Neil Redfearn has left Rotherham with immediate effect, the club have announced.
The 50-year-old leaves the New York Stadium after Saturday's 2-1 Sky Bet Championship defeat to Bolton, which left the Millers third bottom.
Redfearn only won five of his 21 games after taking over in October, losing 14, and Rotherham have won just once in their last eight games in all competitions.
Chairman Tony Stewart said: "It is with a heavy heart that we've parted company with Neil today. As we all know football is a results driven business and with 16 games to go our aim has to be to retain our Championship status.
"Everyone at the club wishes Neil well with his future career and thank him for his efforts and endeavour.
"Our focus now is 100% behind appointing a first team manager as soon as possible."
Redfearn, who replaced Steve Evans, had previously managed Leeds, Scarborough and Halifax.
Source: PA
