  We compare the standard single scalar field inflationary predictions with
those of an inflationary phase driven by a tachyon field. A slow-roll formalism
is defined for tachyon inflation and we derive the spectra of scalar and tensor
perturbations as well as the consistency relations. At lowest order the
predictions of standard and tachyon inflation are the same. Higher order
deviations are present and their observational relevance is discussed. We
discuss the observational consequences of some typical inflationary tachyon
potentials and compare them with recent data. All the models predict a negative
and very small running of the scalar spectral index, and they consistently lie
within the 1$\sigma$ contour of the data set. However, the regime of blue
scalar spectral index and large gravity waves is not explored by these models.
