B1/B2 visa visit limitations

[sridharcvs]

My mother has a 10yr multiple entry visa. She visited us in 2009 sept and left in mar 2010 before her 6 month period ends. Now she wants to visit us again in July/Aug2010.
Is it possible for her to visit within 4 months of her return? or is there any rule that she can only visit once in a calender yr or six months from previous visit?

[immihelp]

There is no official rule.

But if she tries to stay too much in the US, that is in line with tourist visa intentions and will cause problems.