  Dwarf spheroidal galaxies of the Local Group are close satellites of the
Milky Way characterized by a large mass-to-light ratio and are not expected to
be the site of non-thermal high-energy gamma-ray emission or intense star
formation. Therefore they are amongst the most promising candidates for
indirect dark matter searches. During the last years the High Energy
Stereoscopic System (H.E.S.S.) of imaging atmospheric Cherenkov telescopes
observed five of these dwarf galaxies for more than 140 hours in total,
searching for TeV gamma-ray emission from annihilation of dark matter
particles. The new results of the deep exposure of the Sagittarius dwarf
spheroidal galaxy, the first observations of the Coma Berenices and Fornax
dwarves and the re-analysis of two more dwarf spheroidal galaxies already
published by the H.E.S.S. Collaboration, Carina and Sculptor, are presented. In
the absence of a significant signal new constraints on the annihilation
cross-section applicable to Weakly Interacting Massive Particles (WIMPs) are
derived by combining the observations of the five dwarf galaxies. The combined
exclusion limit depends on the WIMP mass and the best constraint is reached at
1-2 TeV masses with a cross-section upper bound of ~3.9x10-24 cm^3 s-1 at a 95%
confidence level.
