Following his omission from the New Zealand world cup squad in 2003 Cullen took the decision to head for Irish provincial side Munster
. Cullen spent the best part of 4 seasons at Munster before retiring in 2007 at the age of 31. This is quite a young age for any rugby player to retire, however his time at Munster was blighted by injury only making 44 appearances in 4 years. Perhaps a sad end to what was surely a fantastic career.