Grimsby boss Mike Newell will let Paul Bolland and James Hunt leave at the end of their current deals.
Both men will be out of contract in the summer and will be forced to look elsewhere for employment in the 2009/10 campaign.
Bolland, who joined the Mariners four years ago, failed to make a first-team appearance last term after suffering a long-term knee injury during pre-season.
Newell was keen to keep the midfielder at Blundell Park over the summer, as he assessed his fitness, but accepts the 29-year-old appears to have received an offer from elsewhere.
"There's nothing we can guarantee him to be honest," he told the club's official website.
"I would have liked to have had a look at him pre-season and see how he comes back.
"But I got the impression that he'd been offered a little bit of security somewhere else, so we wish him well."
Meanwhile, Newell believes that 32-year-old Hunt is in need of regular football as he enters the twilight of his career.
"He's at the age now where he needs a little bit of security and he wants to make sure he's going to play," added the Mariners boss.
"We can't guarantee him that and we thank him for his services."