Andrew McDonald will not be returning to Leicestershire next season because of visa problems.
The Australian all-rounder was named Friends Life t20 cricketer of the year by the Professional Cricketers' Association after scoring 584 runs and taking 14 wickets as the Foxes became domestic Twenty20 champions for the third time.
However, the 30-year-old - who has played in four Tests for his country - will not be back in 2012 to help the county try and defend their title.
Leicestershire will also be without the retired Paul Nixon, while Harry Gurney has left Grace Road to join Nottinghamshire.
"Visa regulations mean Andrew cannot return next season and we thank him for the impact he has made over the past two years," Foxes chief executive Mike Siddall said.
"It's really sad to have to say goodbye to three guys on the playing staff who have made a fantastic contribution to winning the t20 this year and taking Leicestershire into the Champions League."
The county have already moved to plug the gap by recruiting South African batsman Martin van Jaarsveld on a two-year deal from Kent, with an option for a third year.
Leicestershire have also confirmed that Pakistan all-rounder Abdul Razzaq will return next year for the Friends Life t20 competition, after scoring 262 runs and taking 18 wickets in this season's victorious campaign.
Head coach Phil Whitticase said: "Abdul is very relaxed and calm. What he says is very simple but also very clear.
"It is a major boost for us. There are fewer t20 games next season so it will be important that we have a similar type of team. He has shown us all what he can do and we look forward to having him back with us."