Craig Miles, Hamish Marshall, Ian Cockbain and Liam Norwell have signed contract extensions with Gloucestershire.
Nineteen-year-old seamer Miles, having taken 43 first-class wickets this season at an average of just over 30, is now tied to the club until the end of the 2017 campaign.
Former New Zealand batsman Marshall, 34, who has scored 937 first-class runs this summer at an average of 55, has extended his deal until the end of the 2016 season.
Batsman Cockbain, 26, with an average of 33 in this year’s Yorkshire Bank 40 and 23 in the Friends Life t20, and 21-year-old seamer Norwell, who has had an injury-hit summer, have signed until the end of the 2015 campaign.
Gloucestershire director of cricket John Bracewell told the club website: “What fantastic news to have extended Craig’s contract. He is without doubt the best under-20 bowler in the country. With time and effort, Craig will undoubtedly play at the highest level. We must and will provide that support.
“Liam Norwell has had his problems with injuries and we need to get him on the park more. But we recognise his potential as a wicket-taker and will continue to help him overcome the fitness issues.”
Of Marshall, Bracewell added: “Hamish has proved his value to us on and off the field. He is still in our top four in terms of fitness, which is a credit to him and a great example to our young players.
“When you have a young squad it is vital to have the right senior professionals in the dressing room as role models. Hamish is like a father figure to a lot of his team-mates and they trust him.
“Ian Cockbain’s opportunities in four-day cricket have been limited by the fact that our top-order batting has been consistent and we signed a batsman as overseas player in Michael Klinger, who has done very well.
“But in limited-overs cricket Ian has been one of our stars. He has shown he can put bat to ball and does not need time to play himself in.”
Wicketkeeper Richard Coughtrie and all-rounder Paul Muchall have been released.