Performance data for almost 5,000 surgeons in England has been released by the NHS in a move towards greater transparency.
Using the MyNHS website, patients can search for information, including mortality rates for individual specialists.
But some surgeons say the data may be "crude and misleading".
Other critics say that vital data has not been included in the information released.
The MyNHS tool - which has been officially launched - is designed to allow patients and professionals to compare the performance of different NHS services, including consultants.
Patients will be able to search for and compare data on certain surgeons, as well as statistics on local hospital performance, mental health care, social care and public health.
Health Secretary Jeremy Hunt said: "Transparency is about patient outcomes, not process targets.
"It uses the power of a learning culture and of peer review, not blame."
NHS England's national medical director Sir Bruce Keogh told the BBC Radio 4's Today programme that transparency will focus surgeon's minds.
"Surgeons all feel a personal responsibility for their patients - they take it very seriously, they have their patients' best interests at heart," he said.
"[But] previously the risk in a high risk operation has only been taken by the patient. Now it's shared between the patient and the surgeon and that really focuses the mind about the appropriateness of surgery for that particular individual, and well functioning surgery groups will share between them that risk and ensure that the most appropriate surgeon does the operation."
One of the drivers towards greater openness and transparency in the NHS was the Francis inquiry, which looked into failings at Stafford Hospital. The new website is being launched exactly a year on from the government's response to the inquiry.
People can look up consultants by name, by hospital, and by location, a Health Quality Improvement Partnership (HQIP) spokesman said.
A large quantity of the data is already available online, but MyNHS is designed to be more patient-friendly, and includes more details, he said.
For example, there is already information available for adult cardiac surgery for NHS England.
MyNHS includes this data, but there is will also be added details - such as procedure type.
There will also be new data on different types of surgery:
- Information on head and neck surgery was published for the first time on MyNHS on Wednesday
- New information on upper gastro-intestinal surgery and neurosurgery will be published in the first week of December
- The publication of data on urogynaecology in early 2015 will take the total number of consultants on MyNHS to just under 5,000
'Crude and misleading'
Speciality surgeons warned the move could lead to some consultants refusing difficult cases.
Prof John MacFie, president of the Federation of Surgical Specialty Associations, said: "The publication of individual surgeons' performance data is crude and can be misleading, and does not include essential information such as duration of hospital stay and returns to theatre.
"There is now good anecdotal evidence that shows publishing this data has encouraged risk-averse behaviour, which is not in the interest of patients."
Data on mortality rates should only be published after concerns about an individual surgeon had been investigated, Prof MacFie said.
There were also issues with data quality and comparison, Prof MacFie added, including low data volumes, risk adjustment by case, and data accuracy.
"In reality very few deaths can be attributed to surgical error alone, and this data only attracts attention away from institutional failings," he said.
According to clinical data firm Dr Foster, the databases could be missing up to three-quarters of procedures.
Roger Taylor, co-founder of Dr Foster, told the BBC only three of the audits so far had found "outliers" - performance outside the expected range.
The Royal College of Surgeons said the data was part of being open and honest with patients.
Gill Humphrey, chairwoman of the Royal College of Surgeons Patient Liaison Group, said: "Patients can be active participants in their care and use consultant outcomes information to help have an informed conversation with their surgeon and discuss the likely outcome and recovery process from their procedure."