Attracting skilled overseas-trained doctors to the UK will remain "crucial", despite plans to train more healthcare staff here, the doctors' regulator has said.
The General Medical Council (GMC) found that nearly two-thirds (63%) of new doctors in 2022 qualified abroad.
The government launched a major plan in June to train and recruit more healthcare workers in England.
But it will take many years for this to take effect, the GMC says.
NHS England says it currently has 10,855 full-time doctor vacancies - a rate of 7.2%.
Under NHS England's Long Term Workforce Plan, it hopes to recruit and retain "hundreds of thousands" more healthcare staff over the next 15 years. The plan includes spending £2.4bn on additional training places for healthcare workers, with the number of medical school places for student doctors set to double to 15,000 a year.
Trainee doctors must study for five years before they qualify and must then undertake further training.
The health services in Scotland, Wales and Northern Ireland also have recruitment and retention programmes in place. Doctors in each UK nation must be registered with the GMC before they can practise.
Charlie Massey, the GMC's chief executive, said the drive to boost the workforce was "brilliant", but said "it takes a long time to make a doctor".
"We're not going to see the impact of that coming on stream for probably the best part of a decade. And that means we're going to need to rely on doctors who have trained overseas coming to the UK in much greater numbers than in recent years to maintain the workforce that we need to meet the needs of the population."
According to the GMC's new report, it predicts that in 14 years' time, the proportion of overseas-trained doctors working in the UK will be similar to the current level (39 %).
The regulator said it was also concerned about the retention of NHS doctors, and said there were "worrying signs" a growing number plan to leave the profession because of "high levels of dissatisfaction and high risk of burnout".
In 2022, about 2,000 UK doctors left to practise abroad - 15% of the total number leaving the UK profession.
NHS England said its plans include a major drive on retention, including more flexible-working options and career development opportunities.
Mr Massey said it was important "we make sure we are good at embracing and supporting those doctors" when they arrive in the UK.
The regulator runs workshops to help doctors new to the UK adapt to the working culture which overseas recruits are encouraged to attend.
"The more we and our health services can collectively do to support doctors arriving in the UK, the better the chance of retaining their services for longer," said Mr Massey.
Oyku Tural, a doctor who qualified in Cyprus, recently attended a "Welcome to the UK" event at the GMC.
"I know I would need support to adapt to the new system," she told the BBC.
She added that she thought overseas-trained doctors could be an asset to the NHS.
"I feel like we can help better sometimes. I feel like I am a friendly and compassionate person and that's something I can offer."
Dr Sarah Clarke, president of the Royal College of Physicians, said: "Doctors trained overseas have a vital role to play in the medical workforce and without them the NHS would be significantly more stretched than it is now."
An NHS England spokesperson said its long-term workforce plan aims to recruit more doctors, retain those already in the NHS and reform education and training to make it more flexible and deliver the future workforce that patients need.
"The plan, a once in a generation opportunity to put staffing on a sustainable footing, obviously recognises the vital role doctors from overseas have and will continue to have in the NHS," an official said.