This emerges from research by telecoms operator Energis, which also says IT people must do more to push their case for a seat on the board.
The good news is that IT staff are no longer seen as backroom specialists, according to the survey of 200 executives.
Their image has changed partly because of their handling of the year 2000 issue and the rise of e-commerce, e-business and mobile technology.
"Managers we spoke to broadly agree that senior management and board directors now take IT professionals' opinions much more seriously than a few years ago," says Energis director David Shaw.
"However, despite IT managers' increasing influence, their contributions are much less valued by senior business people than those of colleagues in other disciplines."
Shaw points to the fact that directors ranked IT third behind finance and marketing, on a par with personnel and ahead of production, in terms of importance.
In addition, only a fifth of companies had an IT professional on the board - and only 7% predicted that IT would have a seat at board level within two years.
On top of that, figures from Cranfield University, which contributed to the research, show that only 4% of people on MBA courses funded by employers are from IT, compared with 18% from marketing and 18% from finance.
"Several IT professionals said senior managers did not even expect IT managers to understand or show interest in broader business issues, and they found this insulting and frustrating."
He continues, "These findings are very puzzling. Telecoms and IT skills are enabling the e-economy and becoming more important for businesses by the day, yet many companies fail to acknowledge the power and influence of these disciplines in the form of future board-level positions."
Chris Edwards, professor of information systems at Cranfield University, has an explanation. "IT managers are often cultivated as a specialist source of information to the board, and directors are happy to keep things this way."
One view exposed during the research was that many board directors might be worried about their own lack of knowledge and therefore prefer to keep technical people at arms' length.
"Feedback from IT professionals suggests immense frustration at how senior management fail to acknowledge the critical contribution that IT management can make to the business," Shaw says.
A common complaint during the survey was a lack of appreciation of how much time, money and staff was needed for IT projects.
IT people also reported that senior management often or sometimes took wrong decisions because of a lack of technical knowledge.