In September 2014, an opinion survey by the Royal College of General Practitioners found that half of Britons agreed that waiting times were a "national crisis."
Only 23 percent of those polled said there were enough GPs to deal with Britain's growing population.
"We will guarantee everyone who wants it an appointment with a GP in 48 hours," Miliband said.
Last year, a survey by the Daily Mail newspaper revealed that millions of patients waited for up to three weeks to see their GP.
Meanwhile, Miliband added that a Labour government would have an "emergency round" of nurse recruitment and funding for 1,000 extra training places in 2015.
Miliband also said that Prime Minister David Cameron, a Conservative, was a "mortal danger" to the National Health Service (NHS).
The NHS is a traditional hot-button issue in the United Kingdom ahead of the elections. Poll trackers predict a neck-to neck race between the Conservatives and the Labour.
