  The inferred effective temperatures (T$_{\rm eff}$) and surface gravities of
T Tauri stars (TTS) are usually contaminated by the presence of a non stellar
continuum emission (veiling) and the strong chromospheric activity
characteristic of these objects. In this work, we develop a method to determine
T$_{\rm eff}$'s and surface gravities (log$\,g$) of a group of TTS. This method
is based on the comparison between observed and theoretical molecular and
atomic line depth ratios being therefore insensitive to the influence of
veiling. We show the strong dependence of our line depth ratios upon gravity
and temperature. The resulting gravities, as expected for TTS, average between
the values of dwarf and giant stars. Previously published gravities for each of
our stars vary widely due in part to the differences in the adopted visual
extinction, veiling (if ever considered) and methods of assessing the stellar
luminosity. Our values of T$_{\rm eff}$ and log$\,g$ have the uniqueness of
being entirely derived from high resolution data and are not affected by
circumstellar extinction or veiling when line ratios are used. They therefore
serve as more reliable input parameters for future spectral synthesis analyses
of T Tauri Stars requiring model atmospheres. We provide a table relating
theoretical line depth ratio with T$_{\rm eff}$ and log $\,g$ for easy
assessment of TTS fundamental parameters.
