The singer announced that she is not able to perform tonight in Cardiff and has postponed her planned gig in Blackpool on September 8.
The 'Set Fire To The Rain' star has been forced to cancel the dates by her doctor as she has not fully recovered from bronchitis.
The London-born songwriter had previously cancelled two dates earlier this week, as well as a planned performance at last night's Mercury Prize ceremony.
Her label XL Recordings stated: "She had cancelled her performance at The Mercury Awards last night in the hope she would be able to continue her live dates, but has been told by her doctors that she is still not well enough to perform."
They added: "The shows will be rescheduled at the earliest opportunity and all original tickets will remain valid. Refunds will be available from the point of purchase."
The star's next planned show is at Wolverhampton's Civic Hall on September 10.
Adele apologised to fans on her official blog earlier today, saying that her illness leaves her "breathless", making it "hard to hold any of [her] notes".
Watch the music video for Adele's 'Rolling In The Deep' below: