Gillingham have put midfielders Charlie Lee, Chris Whelpdale and Steven Gregory and striker Antonio German on the transfer list.
Gills boss Martin Allen is keen to add to his squad following their winless start to the 2013/14 League One campaign and needs to move some players on in order to free up funds for new signings.
He told the club's official website: "I need to make some changes. I need to add some players and the group needs to be freshened up.
"I have also told all of the others that after Sunday's game I will look next week with a view to be making potential possible future changes. We need to improve our starting 11.
"The logic behind that is that we need to raise some money to improve our team, it's as simple as that. They are great lads, all four of them. They have done a great job for our club but changes need to be made.
"I know the players we would like to bring in and it needs freshening up, sharpening up and we need to be better. I don't think anyone can argue with that, we need to try and make it better and that's my job.
"We train on the training pitch, we work in the gym, we work as a team, we work with individuals but it needs to get better and that's what you have to do sometimes.
"I suppose they are not very happy but I do my very best to make sure our players are always happy. I look after them, I treat them well, I speak to them properly but the bottom line is that we need to do something that will help us win games and these are the decisions you have to take on."