Some patients are waiting for up to a month before seeing their GP, figures show.
The research, published by the Sunday Mirror, reveals 15 million appointments were delayed by more than 28 days in the 12 months to August.
A similar number were kept waiting between 22 and 28 days and more were only seen between 15 and 21 days.
This means a total of 55 million GP visits took longer than a fortnight.
It comes after a report warned Britain is heading towards a 7,000 GP shortage within five years because of problems with training and retention.
Liberal Democrat health spokesman Norman Lamb said the shortage of GPs is leaving patients stranded when they could have serious health issues.
“Our GP service is at breaking point due to the lack of funding and the failure by government to solve the problems with recruitment and retention,” he added.
Professor Helen Stokes-Lampard, chair of the Royal College of GPs, said GPs and their teams will see well over a million patients every day. “But whilst we are working ever harder to deliver care to patients, the number of GPs is falling,” she stated.