More than 90% of people believe that admitting to a mental health condition could damage their career prospects.
The result is that most give a different reason to their employer, if they need time off from work, a poll for Mind has found.
KPMG's Nick Baber, a director in the Financial Services Consulting team who has suffered from depression, argues that creating a culture of openness, early intervention and support in the workplace is critical if UK plc is to remove the stigma attached to depression and mental illness.
He said: "The stark reality is that so much energy is spent by individuals pretending to be something they are not, that mental and physical health, performance and productivity suffer as a result.
"It would be far better if employees were comfortable enough in their working environment to be themselves, but this will only happen if senior business leaders with experience of mental health problems tell their own stories and implement performance indicators which measure and report on progress in the workplace.
"The taboo associated with openly discussing depression will also be easier to remove if organisations commit to providing mental health training for anyone with line management responsibilities. After all, knowing how to support a colleague is critical first step in helping them deal with their situation at work. With reports suggesting that mental health problems cost the UK economy £26 billion per year** this is no longer an issue British business can ignore. Doing so will prove too costly - both for organisations and the mental well-being of their staff."
Stephen Frost, UK Head of Diversity & Inclusion at KPMG, said: "Being comfortable in your own skin is a key ingredient for career success and employees need to know that they will not face career road blocks if they 'come out' and admit to having mental health problems. Organisations want to attract and retain the best people - and the only way to do that is to be inclusive. What matters most are the skills an individual brings to the table, but it is the employer's duty to provide them with the support to keep them there."
The British Medical Association has provided a burnout diagnosis questionnaire for doctors, which is available online.