The survey shows that staff believe men are more likely to get the most senior marketing positions while women will have to settle for middle or lower managerial roles.
In large businesses, 60% of women claim they have needed qualifications, commitment and determination to succeed, yet lesser-qualified men still ended up in the more senior promotions.
Nonetheless, the Marketers' Forum reports that smaller, newer and more entrepreneurial employers appear to have a more balanced workforce both in their marketing departments and across their businesses.
These findings come only days after the Chartered Institute of Marketing reported that the pay gap between men and women has increased by 8% since 2007.
Quentin Crowe, managing director of the Marketers' Forum, said: "This is an astonishing finding. I am surprised that large businesses have still not moved with the times."
Sexual discrimination is rife in large businesses
More than three quarters (78%) of men and women working in the marketing departments of FTSE 100 companies feel sex discrimination is present throughout their business, according to the Marketers Forum.
