I saw a similar stat in another thread some months ago - this one which was quoting that men are the victims in 2 out of 5 cases reported.
This was much higher than I'd thought - so I did a bit of digging at the time and this was what I found (on page 2 of the thread, but c&ping here)
"I looked up the factbox on the BBC site as a result of [the OP]. I'd never heard that "two in five of all domestic violence victims are men" before. I thought the proportion was much, much lower than that.
The source of the fact seems to be this organisation - of which I have also never heard before - www.parity-uk.org/index.php . Their stated aim is to fight for equal rights for men and women, although it's fairly clear that they think that it's MEN who are unfairly discriminated against and want to redress the balance.
To that end, they've got a whole piece on domestic violence against men on their site and quote extensively from the British Crime Survey 2005/06. This bit caught my eye:
"In the longer term, since the age of 16, and again excluding stalking, the survey found that 28.1% of women and 17.5% of men reported having suffered non-sexual partner abuse, a proportion of male victims of about 38%. Of these, 19.1% of women and 10.4% of men reported having suffered actual force, a proportion of male victims of about 35%, which was designated ?severe? in the case of 13.7% of women and 8.7% of men, a proportion of male victims of about 39% - the same as in 2004/05."
This is presumably the source of the 'two in five' stat (39% roughly equals two in five)
But I did a bit more digging, and found this interesting Home Office analysis of the BCS, which included a bit more detail on severity and number of incidents of domestic abuse:
"There were an estimated 12.9 million incidents of domestic violence acts (nonsexual threats or force) against women and 2.5 million against men in England and Wales in the year prior to interview."
So if you go on incidents of abuse, men are victims in 16% of cases. Which is a bit more in line with what I had always thought."
It's a bit of a tangent, but it backs up what frothy's saying.