We present results of a quantitative spectral analysis of a sample comprising eleven hydrogen deficient post-AGB stars of the spectral type PG 1159 with state-of-the-art NLTE model atmospheres. For all objects high resolution spectra obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) are available. The FUV spectra of PG 1159 stars are dominated by lines of helium, carbon and oxygen, and for the first time we also identified lines of several trace elements as sulfur and silicon which allow to determine the abundances of light metals in the atmospheres of these stars. As these stars show nuclear processed former intershell matter on their surface, the determined abundances also allow us to constrain the predictions of evolutionary models and element abundances in AGB stars.