Junior doctors marching through the centre of Newcastle said both the public and their more senior colleagues are supporting them in their row with the Government over contracts.
Up to 4,000 doctors and their supporters turned out for the protest on Saturday afternoon, organisers said.
Organiser Dr Tom Gorman said: "We've had fantastic support from both the public and the consultants.
"We've had lots of cheers and handshakes. Lots of people coming to talk to us.
"It is quite a complex issue but I think people understand the general idea that no-one wants to be treated by tired doctors."
Dr Gorman, who is a GP trainee in Co Durham, said junior doctors had travelled from as far as Manchester and Glasgow for the demonstration which began outside the city's medical school.
He said he was particularly pleased by the support from consultant colleagues who joined the march or covered juniors' shifts so they could attend.
The Government has said it plans to impose a new contract on junior doctors, up to consultant level, next summer.
The contract will reclassify doctors' normal working week to include Saturdays and up to 10pm every night of the week except Sunday.
Medics argue they will lose out financially as evenings and Saturdays will be paid at the standard rate rather than a higher rate.
They say this amounts to pay cuts of up to 30%.
Health Secretary Jeremy Hunt has indicated to the British Medical Association (BMA) that he will consider extending the current proposals so that more working hours on a Saturday could be paid at a higher rate.
But the BMA argues that Mr Hunt has failed to offer any guarantees on key issues such as pay and protection for doctors who wish to work less than full-time or take parental leave.
Earlier this week, the BMA said junior doctors are to be balloted on industrial action next month.
Speaking at PMQs on Wednesday, Mr Cameron said: "The plans that we have are not for increasing junior doctor hours.
"They are not for cutting junior doctor pay. They are not even for making savings in the overall amount that junior doctors receive.
"It's about making sure the health service works better for doctors but above all for patients."