Monty Python's reunion show sold out in just 43.5 seconds on Nov 25.
The British comedy troupe announced last week they had reformed for a one-off live performance but with demand for tickets so high the group have added a further four dates at The O2 in London, which has a 20,000 capacity.
Member John Cleese, 74, had hinted they may do more than one performance, but only if public interest justified it.
Speaking on 'The Andrew Marr Show' on Sunday (24.11.13), Cleese said: "If we can add some shows we will but it will entirely depend on if the tickets sell. We always say that when we get together, we laugh more than at any other time in our lives so it's kind of fun."
When the Pythons - also comprised of Terry Jones, 71, Terry Gilliam, 72, Michael Palin, 70, and Eric Idle, 70 - announced their return last week they said there would be some new material in the show and some older jokes would be updated for a modern audience.
However, Cleese insists they must be careful about what original stuff they do include because their audience wants to watch and laugh at their greatest sketches, gags and songs from their TV series 'Monty Python's Flying Circus' and films.
Cleese said: "We have to be very careful about doing new stuff. It's not a theatrical presentation, it's like a rock concert and when people go to rock concerts they want to hear the old songs and they're actually literally disappointed if you do new material."
Sixth Monty Python member Graham Chapman died in 1989 at the age of 48 but he will feature in the 'Monty Python Live (Mostly) stage shows.