  We discuss an interacting tachyonic dark energy model in the context of the
holographic principle. The potential of the holographic tachyon field in
interaction with dark matter is constructed. The model results are compared
with CMB shift parameter, baryonic acoustic oscilations, lookback time and the
Constitution supernovae sample. The coupling constant of the model is
compatible with zero, but dark energy is not given by a cosmological constant.
