More than 17,000 deaths a year in the UK are unnecessary and due to poor NHS performance, campaigners say.
NHS funding has been increasing in recent years
The TaxPayers' Alliance compared World Health Organization data for five leading European countries.
It found the NHS had 17,157 extra deaths in 2004 compared with the other countries' average when taking into account age and burden of disease.
The government said investment in recent years had cut waiting lists, improved choice and saved lives.
Researchers for the TaxPayers' Alliance, a group which is campaigning for lower taxes, compared the UK with France, Germany, the Netherlands and Spain.
They looked at "mortality amenable to healthcare" - the number of deaths from certain conditions and at certain ages that healthcare can reasonably be expected to avert.
The rate in the UK was 135 per 100,000 people, compared with an average of 107 across the five countries. France had the best rate at 91.
The report said if the difference between the UK figure and average was applied to the whole population, it would equate to 17,157 deaths - five times the number that die in road accidents.
It said improvements in mortality rates had been seen across the continent since the 1980s.
But it said the falls in the UK had remained steady throughout the Thatcher, Major and Blair administrations, despite the record increases in NHS funding seen under Labour.
Report author Matthew Sinclair said: "Thousands are dying every year thanks to Britain's health service not delivering the standards people expect and receive in other European countries."
The report recommended NHS bodies be given more independence from central government.
Shadow health secretary Andrew Lansley said: "Millions of pounds of taxpayers' money has been spent but real success on a European level has not been achieved.
"This international comparison shows the extent of Labour's failure to deliver the many promises made to patients in the UK."
But the Department of Health said the extra investment over the last 10 years had provided more than 100,000 extra doctors and nurses and led to cuts in waiting times and improved access.
Health minister Ben Bradshaw added: "Mortality rates have been falling steadily and the UK has been narrowing the gap with the best continental EU performers."