The petrography, mineral chemistry and petrogenesis of a sample from the Weissenstein eclogite, Bavaria, Germany, has been investigated. The total mineral assemblage comprises garnet, clinopyroxeneI+II, quartz, amphiboleI+II, rutile, phengite, epidote/allanite, plagioclase, biotite, apatite, pumpellyite, titanite (sphene), zircon, alkali feldspar and calcite. Textural observations combined with geothermobarometry (Fe/Mg distribution between clinopyroxene/garnet and phengite/garnet; jadeite-content of omphacite, Si-content of phengite, and An-content of plagioclase) provide indications of two different stages in the metamorphic evolution of the rock. The main phengitequartz-eclogite mineral equilibration occurred at minimum P=13-17kbar, minimum T=620±50° C; the retrograde symplectite stage (clinopyroxeneII, amphiboleII, biotite, plagioclase) occurred at Ptotal between 12 and 8.5 kbar. Reactions of the symplectite stage are: (1) phengite (core) + Na2Oaq + CaOaq=phengite (rim) + biotite + plagioclase + K2Oaq + H2O (2) phengite (core) + clinopyroxeneI + Na2Oaq=phengite (rim + biotite + plagioclase + amphiboleII + SiO2 + K2Oaq + CaOaq + H2O (3) clinopyroxeneI + SiO2 + K2Oaq + H2O=clinopyroxeneII + plagioclase+amphiboleII + Na2Oaq + CaOaqThe phengite decomposition produces H2O, whereas the clinopyroxene decomposition consumes H2O. The estimated P-T-conditions for the Weissenstein eclogite are in the same order of magnitude as those for other eclogite bodies from the Alps and Caledonides believed to be related to subduction processes.