People in the UK face longer waits for non-emergency surgery and struggle to see GPs out-of-hours compared with other western countries, a survey says.
UK health care has been changing in recent years
But they are the least likely to have problems with medical bills and insurance, the poll of over 12,000 patients in seven countries showed.
Experts said the study, carried out by the Commonwealth Fund, a US think tank, presented clear challenges to the UK.
The government said care was improving, but it was aiming to be the best.
Some 55% of UK patients said they had had difficulty getting access to GP care on weekends and nights.
This was worse than Germany, the Netherlands and New Zealand and comes amid mounting criticism of the arrangements within the NHS.
A new GP contract, which started in 2004, allowed family doctors to opt out of providing out-of-hours care.
But the changes, which has seen private firms take on the role in many places, have been accompanied by a rise in complaints.
The UK also has the worst record for waiting times with 15% having to wait for more than six months for elective treatment.
Canada was the next worst on 14% and the Netherlands the best with 2%.
It is not the first time waiting times in the UK have been compared unfavourably with those in other countries.
When Labour came to power in 1997, it made hospital waits a major priority and by next year ministers have promised that no-one will wait longer than 18 weeks for treatment.
Over half of those quizzed also said "fundamental changes" needed to be made to the system, with 15% saying it should be completely rebuilt.
These were similar figures to the other countries with the exception of the US which was much higher and the Netherlands which was lower.
However, UK patients were the least likely to have problems paying medical bills. Just 1% said they had had difficulties, compared to 19% in the US and 8% in both Australia and New Zealand.
A Department of Health spokeswoman said: "Over the last 10 years there has been record investment in the NHS.
"That money is paying for more staff and better pay, 1m more operations a year, over 100 new hospitals and improved access to healthcare."
But she added: "Delivering the highest quality of care for all, as good or better than any country in the world, must be a fundamental goal of the NHS."
Patients from Australia, Canada, Germany, the Netherlands, New Zealand, the UK and the US were questioned.