About 37,000 women have gone missing from IT between 2001 and 2007, according to the British Computer Society (BCS).
The BCS said such a large number could help to alleviate the industry's much publicised skills shortage. In 2001, 23% of the UK IT workforce was made up of 229,440 women.
Last year this number had fallen to 192,580, a fall of 6%. This was despite the overall number of IT professionals growing in the same period.
The BCS has published a guide to retaining female IT workers, aimed at HR directors and senior managers. It contains case studies to help organisations retain employees who wish to take a break to care for relatives or children.
BCS Women's forum manager Jan Peters says, "Credit crunch or not, IT industry leaders are still predicting skills shortages. And yet the number of women exiting the IT profession continues to rise alarmingly, mainly due to the lack of flexibility offered by employers."