Speaking at the Edinburgh Film Festival, McGregor, 44, described the opportunity to work with the original cast and director again as "extraordinary", according to The Hollywood Reporter.
The actor added that any follow-up film could be the next movie that could take him back to shooting in Scotland.
"It might be the film that brings me back. I would be up for it, I've said that to Danny. Everybody has talked about it and speculated about it, but I don't if it's happening yet. I've not seen a script and I don't know if there is one," said McGregor.
The film was the second of three collaborations between Boyle and McGregor, who also made "Shallow Grave" and "A Life Less Ordinary together", but the pair famously fell out after the director cast Leonardo DiCaprio as the lead in "The Beach', a part that was originally intended for McGregor.
The idea of a sequel to "Trainspotting" has been around since the author of the original books, Welsh, wrote "Porno", the literary follow-up. McGregor has for years dismissed any suggestion of working on the project, but two years ago serious talk arose that Boyle, screenwriter John Hodge and producer Andrew MacDonald were working on a loose adaptation of "Porno".