Mark Hammett's tenure at the helm of the Cardiff Blues has ended just six months into a three year contract.
The former Hurricanes coach has endured a tough time in Wales, with his side winning just four of 15 matches since taking the job.
The club insists Hammett has not been sacked, but is leaving for personal reasons with his mum not very well.
In a statement, the Board of Directors at Cardiff Blues said it was disappointed at the move but had been accepted.
Richard Holland, Chief Executive at Cardiff Blues, said: "We were naturally very disappointed and surprised when Mark informed us of his decision. However, we fully understand the personal reasons he has given and he has our full support.