Romelu Lukaku, Gerard Deulofeu and Gareth Barry have all made big impacts since joining on loan from Chelsea, Barcelona and Manchester City, respectively.
And Martinez believes their success will only help Everton in the future when it comes to bringing players in.
"They have seen the other loanees and how well they have been looked after," said Martinez.
"It hasn't happened with the clubs in the UK, but it has come from abroad.
"We have had calls from clubs asking about taking their players for next season.
"They see it as a perfect step up in their career.
"Put yourself in the position of a director of football who has spent £20million on a youngster, but there's no place for him in your team.
"You aren't going to send him somewhere he isn't going to develop, or to a club with a different style."
Lukaku's move, particularly, has been a big success as he is currently one of the top scorers in the Premier League with eight goals to his name already this season.
"Chelsea are delighted with Romelu. He can't play against them, and the other week he helped take two points off Arsenal, and three points off Manchester United," Martinez said.
"If you're Chelsea, that's perfect."