The chair of the Royal College of GPs (RCGP) predicts there will be fewer clinical commissioning groups (CCGs) than primary care trusts (PCTs) as the reforms 'bed in'.
Dr Clare Gerada said mergers between CCGs during the NHS Commissioning Board's authorisation process is "inevitable" if the organisations are to survive.
"Of course the number of 211 CCGs is going to go down as the authorisation process reaches its climax," she said.
"They will have to merge to pool resources and risk."
Dr Gerada also predicts the end number of CCGs will be lower than that of the number of PCTs (152) before the reforms were unveiled in 2011.
"I think 150 CCGs will be too many as the reforms go live," she said.
An NHS CB spokesperson said, "There are 211 proposed CCGs, currently going through authorisation, which cover the whole of England. There are no plans for changes to this configuration."