Nearly one in three health professionals have refused to be named over payments they received from drug firms.
A new database that can be searched by members of the public - aimed at improving transparency in the pharmaceutical industry - contains the names of around 16,000 doctors, nurses and other health workers who have received payments or benefits in 2015.
Around 6,000 healthcare organisations, such as NHS trusts, are also included in the list. But almost one in three (30%) medics refused to give consent for their names to be included in the voluntary scheme. They accounted for a spend estimated to be around £30 million.
The disclosureuk.org.uk database shows payments from 109 pharmaceutical companies working in the UK, including giants GlaxoSmithKline, AstraZeneca, Roche and Pfizer.
In 2015, the industry spent a total of £340.3 million working with health professionals and organisations, with AstraZeneca spending the most (£41.9 million).
Of the total spend across all firms, £229.3 million (67%) was spent on research and development, mostly on clinical trials.
The remaining money included £46 million given to healthcare professionals for consultancy fees and services. This included doctors sitting on advisory boards for the development of new medicines or technologies, giving speeches or chairing meetings.
A further £14.8 million was spent on medic registration fees, travel fees and accommodation to health conferences and meetings, both in the UK and abroad.
Some £31.4 million was spent on paying for events, such as payments to NHS bodies that run events.
Where individuals refused to give consent for their name to be used, payments have been published on an aggregate basis.
Mike Thompson, chief executive of the Association of the British Pharmaceutical Industry (ABPI), which is publishing the database, thanked those doctors who had disclosed their names and asked those who had not disclosed "to reflect on that".
He said he felt confident that more doctors and health workers would disclose their names next year, adding that it was important for the public to see the "huge benefit" of work between the industry and healthcare professionals.
He added: "These partnerships matter and help our industry bring the right medicine to the right patient at the right time so we can improve quality of life and, in many cases, save lives.
"Getting advice from doctors, nurses and health professionals across the NHS helps us do this - we can't do it alone.
"We believe it's right we pay for that expertise and insight, as this is work which health professionals undertake often in addition to their day job in the NHS."
Firms must publish the data annually as part of their membership of the ABPI.
The latest figures showed the average amount invested per company was around £3.1 million, with 84% spending less than £5 million.
Professor Alan Boyd, president of the Faculty of Pharmaceutical Medicine, said: "It is vital that the companies that are researching and developing new medicines do work closely with the doctors that will eventually prescribe these medicines for advice and take account of their experience and expertise.
"It is only right that these doctors are compensated for the time they give in doing this, as this is normally done outside of their normal working hours.
"However, I think that all the information should be made public and all doctors should declare whether or not they have received any payments from pharmaceutical companies on an annual basis."