mirroring fails

Hi there!
I modeled the half of a human body and now I try to mirror the whole thing. But either I loose detail information when I use the mirror modifier or the normals are messing up when I copy the vertices and mirror them in edit mode.

Thanks for help!

You need to show us something at the very very least. The mirror modifier does not remove any geometry information at all so need to clarify what ‘lose detail’ means. Do you understand what the mirror modifier does and its settings ? http://wiki.blender.org/index.php/Doc:2.6/Manual/Modifiers/Generate/Mirror

Show screenshots in object and edit mode, post a link to your blend file

Thanks for the quick answer! Here are screenshot before and after applying the mirror modifier and after copying the vertices and inverting the normals:

there we are…