  We report on the first observation of electromagnetically induced
transparency (EIT) in a ladder system in the presence of a buffer gas. In
particular we study the 5S1/2 - 5P3/2 - 5D5/2 transition in thermal rubidium
vapor with a neon buffer gas at a pressure of 6 Torr. In contrast to the line
narrowing effect of buffer gas on {\Lambda}-systems we show that the presence
of the buffer gas leads to an additional broadening of (32 +/- 5) MHz, which
suggests a cross section for Rb(5D5/2)-Ne of {\sigma} = (7 +/- 1) x 10-19 m2.
However, in the limit where the coupling Rabi frequency is larger than k the
collisional dephasing a strong transparency feature can still be observed.
