Ferguson believes that Kenyon - who left the club to become a part of Roman Abramovich's Chelsea - 'didn't get the job done' when he failed to lure Brazilian Ronaldinho to Old Trafford.
After looking set for England, Ronaldinho plumped for a move to Barcelona, and Ferguson believes that United have missed out on a major player.
"It was disappointing not to get Ronaldinho," admitted Ferguson in the News of the World.
"There was a problem with his brother, who was his agent, but Peter Kenyon, who was chief executive then, didn't get the job done.
"There have been others - like Alan Shearer and Paul Gascoigne - but we did get Eric Cantona for example.
"We are constantly in search for the player who will make the difference."
Ferguson has faced criticism for not bringing in a defender in the winter transfer window - when it became clear the club would be without the services of Rio Ferdinand for the second half of the season.
"We could have identified another defender to bring in, but it is extremely unlikely that we could have got anyone of the required quality during the transfer window."
