Suzanne Deans was won over by the sales pitch of representatives from Combined Insurance Company of America, Colonial Mutual, and Britannic, and briefly started a pension with each in turn.
When paying into her first private pension, in December 1989, Ms Deans, 26, cancelled premiums into her occupational scheme.
She later had doubts about each insurance company and stopped making contributions. But she did not start up her NHS scheme again, thereby losing her pension entitlements for those years.
Ms Deans, who works at the Queen Alexandra Hospital in Paisley, Scotland, said: 'I'm really upset. I've lost my NHS pension because I listened to people who told me their products were much better than the others available.'
Her problems began in late 1989 when Ms Deans, who was then married, was persuaded to start a personal pension, paying pounds 48.75 a month to CICA, based in Kingston upon Thames.
She cancelled her application within weeks and received a full refund of her premiums. The company's compliance officer, Lionel Phillips, said opting out of her NHS pension could have been considered as good advice.
In September 1990, Ms Deans was visited by a representative of Colonial Mutual, who convinced her to sign up for a private scheme again. The company said it was not aware of any previous pension arrangements. But before her standing order was even activated, Ms Deans cancelled it.
She said: 'At about that time, I was visited by someone from Britannic who showed me figures and convinced me that his company's scheme was far better than the Colonial Mutual one. I told him that I did not want to be paying two standing orders at once.
'He said that would be no problem. All I had to do was cancel the Colonial Mutual order and fill in a new one with Britannic. There was no point in mentioning my other pension on the application form.'
Ms Deans's claim is denied by Brian Shaw, general manager at Britannic. He said her application form, which the company has kept, states that Ms Deans did not have a pension at the time. He added that she might have been confused when she signed it.
In mid-1992, Ms Deans's preserved pension from the NHS was also transferred to Britannic. Then, a year ago, she stopped payments to Britannic when she moved home.
She has not resumed contributions to the NHS scheme and has now been opted out for four years: 'I keep meaning to start up again, but once you are out, it is easy to just let things go,' said Ms Deans.
Her government rebate for opting out of the state earnings-related pension for two years is still lodged in a Colonial Mutual personal pension.
Her case has been taken up by her union, the Royal College of Nursing, after she called its telephone hotline last week.
Martin Burke, who has been co-ordinating the hotline, said some of Britain's best-known companies, including Prudential and Pearl, are among those named by hundreds of worried nurses as having persuaded them to shift their occupational pensions into private schemes.
'You can tell that these pensions were not bought by nurses who understood what they were doing. They were sold by people who manipulated that ignorance,' he claimed.
'This case is a striking example of what happens when young and potentially confused people come face-to-face with smooth-talking salesmen.'
Almost all of the hotline callers said they were sold a personal pension by a company representative rather than an independent financial adviser, Mr Burke added.
Prudential has spent pounds 300,000 on a publicity campaign informing the public that its own activities in this area are above board.
Steve Bee, the company's pensions manager, said: 'It is not always the case that nurses should remain in the NHS scheme. Sometimes the additional benefits, such as a spouse's pension when the pension-holder dies, are not needed.' Even so, Prudential refuses transfer business in 40 per cent of cases it examines.
A Pearl spokesman admitted some nurses might have been wrongly persuaded to opt out of their NHS schemes: 'The situation today is not what it was a few years ago. We would not do so now.'
The company is now half-way through a review of 200,000 of its personal pensions, 50 per cent of all the schemes it has sold in the past five years.
Several thousand have been identified as ones where compensation may have to be paid. The sum involved is likely to run into millions of pounds, the Pearl spokesman added.