Hi all, Iam trying to import BVH files to work on an already rigged character. When I import the Bvh file, blender has two options whether to import as an empty or as amrmature. If I import as an:

1. Armature: A new armature is added to the scene in the + Y direction from front view while character is standing up straight in the +Z direction. When press alt A, the newly added armature plays but does not affect the rigged character.
2. Empty: A series of empties is added to the scene also in the +Y direction and when AltA, it does not affect the mesh.

Please can anyone help me on how to attach BVH files to a rigged character.

That basically sounds like my experience in the past.  I gave up on it for the time being. 

I believe I toyed around with trying to make the bones in my character 'track to' the respectable empties.. But I believe the fact that it was rotated 90 degrees in the wrong direction proved to be a difficult hurdle.

If you import as ARMATURE you have to relink the armature to the mesh.

If you already have a working armature that is deforming a mesh, you can import as EMPTIES and simply parent the empties to the controls of your working character rig.

So how do you relink the aramture to the mesh

Just use simple parenting.

Say out have a working rig with a foot contol called "l-foot"
Say you have imported  a rig of empties and the empty is called "mt-l-foot"

Select "l-foot" in the 3D window.
Press the N-Key to bring up numeric input and type "mt-l-foot" into the parent field.

OK. Thanks a lot