Why are the front faces of my model disappearing?

[pajhonka]

I'm using Zbrush for the first time and when I try to open my OBJ in Zbrush, the front faces seem to be transparent (see image). When I export the model and bring it back into Maya, however, the front faces are visible. Is this a setting I need to change or something? Thanks.

[jayguy]

You have your normals reverced. Try going to the polygon menue in Maya go to "Normals" click "Reverse" with your mesh selected then export your mesh to ZBrush. I had the same issue, should work.