How can I mirror a GUI Texture?

I use GUI.DrawTexture function to draw a texture on the screen, is there any method to mirror this texture?

You can use DrawTextureWithTexCoords:

This draws a texture the normal way:

GUI.DrawTextureWithTexCoords(new Rect(0, 0, 100, 100), _Texture, new Rect(0, 0, 1, 1));

This draws a texture, mirrored horizontal:

GUI.DrawTextureWithTexCoords(new Rect(0, 0, 100, 100), _Texture, new Rect(0, 0, -1, 1));

Just use the texture-coördinates Rect to adjust the mapping of your texture. Hope this is what you need.

Cheers

You should be able to pass a negative value for the width of the rectangle.