He made his Ospreys debut against Cardiff Blues last August, and to date he has made fifteen appearances for the region. He was capped 52 times for Wales, scoring 11 tries including the first one at the Millennium Stadium when Wales played South Africa in 1999. He enjoyed a particularly successful period in a Swansea shirt where he was part of a side that won two league titles and tasted cup final success against Llanelli in 1999. The following year he was voted Welsh Player of the Year.
Speaking today, he said: "I just feel that now is the right time. I'm 35, I've had an enjoyable and successful career and I feel that opportunities for me to get regular rugby only going to get less and less so I think its best to make the decision myself rather than have someone make it for me.
"I've got no immediate plans for the future and I'm going to take a short break, but I can't see me playing any further rugby at a lower level. I've suffered with knee problems throughout my career so it's a case of quitting while I've still got my health. I would like to stay in the game in an administrative role if possible, I've got chartered accountancy qualifications and it would be great if I could combine that with rugby somehow.
"I've got many happy memories of my time as a player to take with me. As a young boy I always dreamt of playing for Wales but never imagined it would be true, so to not only do that, but to captain my country, score the first try at the Millennium Stadium and to win a Grand Slam are fantastic memories. Other high points that I'll look back on are going on the 2001 Lions tour and winning the Guinness Premiership at Sale."
Ospreys Head Coach Lyn Jones added: "On behalf of everybody at the Ospreys, I'd like to wish Mark all the best for his future. He's enjoyed a great career at the highest level, and has had success in both Wales and England, as well as internationally. His time at the Ospreys has only been a short one, but his professionalism has always shone through and he has been a pleasure to work with."