Gahan is thought to be suffering from gastroenteritis but it is not known if the other dates on Depeche Mode's current tour will also not be able to be staged.
The electro-pop group Depeche Mode, best known for hits like Personal Jesus and Just Can't Get Enough, are due to appear in concert in Istanbul, Turkey, on Thursday, before travelling onwards to Romania for a gig in Bucharest on Saturday.
Tuesday's concert, for 20,000 fans at Athens' Terra Vibe park, had to be pulled at the last minute after Gahan was taken ill.
The latest update on the Depeche Mode website announces: "Even though everyone hoped for the singer's speedy recovery and the rescheduling of the band's show for today, May 13th, 2009, according to the information received by the band's management and the doctor on duty, the artist's health condition does not allow it."
