According to geochemical data the pegmatites from the Western Tatra Mts. (S-Poland) crystallized from a water-saturated melt, peraluminous in composition, rather poor in trace elements, at temperatures below 700 °C. Their origin is connected with partial melting of metamorphic rocks. A Rb/Sr whole-rock isochron study indicates that the pegmatites under consideration were emplaced during the early Hercynian period. They yield an age of 345±9.5 Ma and initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70625±0.0002. The low value of the initial Sr isotope ratio suggests a significant admixture of mantle-derived material in the parent rocks melted during metamorphic processes in the Western Tatra crystalline complex.