Swindon have told Alan Connell, Jonathan Smith, Mattia Lanzano and Lee Cox they will not be offered new contracts for next season.
The quartet have been placed on the transfer list by Robins boss Paolo Di Canio having been deemed surplus to requirements at the County Ground.
Striker Connell joined the club for an undisclosed six-figure sum from Grimsby last summer and Town's decision to part with his services comes as a surprise given he went on to top the club's scoring charts in his first season, bagging 13 goals in 44 appearances in all competitions.
Midfielder Smith was another summer signing 12 months ago, going on to make 48 appearances in total, as was goalkeeper Lanzano, who went on to enjoy seven outings.
Midfielder Cox, meanwhile, who also played seven times last term, only joined the club in January on a two-and-a-half year deal from Inverness for an undisclosed fee.
The news comes with Di Canio having already added seven new faces to his squad this summer, despite Town clinching the npower League Two title last season.