Neogene calc-alkaline magmatites (from basaltic andesites to rhyolites including mafic cognate enclaves) of the Rodna-Bârgău subvolcanic area (East Carpathian arc) are evaluated on the basis of new mineral compositional data, major and trace elements, as well as Sr and O isotope data. Two different series of rocks have been separated. The magmas of the medium-K series had a rapid ascent toward the surface, as proven by the presence of primary garnet bearing rocks, or by the sporadic occurrence of mafic cognate enclaves. The δ¹⁸O values of amphiboles vary from 4.2 to 5.4 ‰ (SMOW). The δ¹⁸O value measured on garnet is 4.3 ‰. The range of ⁸⁷Sr/⁸⁶Sr ratios is from 0.70588 to 0.70887. The decrease of the δ¹⁸O values as ⁸⁷Sr/⁸⁶Sr ratios and SiO₂ increase is interpreted as a progressive contamination of a mantle derived magma with a contaminant depleted in δ¹⁸O and enriched in ⁸⁷Sr/⁸⁶Sr (i.e. hydrothermally altered lower crustal rocks). Within the high-K series the presence of intermediate magma chambers where assimilation-fractional crystallization processes took place is considered. The δ¹⁸O values measured on clinopyroxenes vary from 4.6 to 5.7 ‰ and on amphiboles from 3.8 to 6.7 ‰. The range of ⁸⁷Sr/⁸⁶Sr ratios is from 0.70605 to 0.70950. The covariation of the δ¹⁸O values and ⁸⁷Sr/⁸⁶Sr ratios is scattered. The highest δ¹⁸O values correspond to the highest ⁸⁷Sr/⁸⁶Sr ratios and are consistent with assimilation of the local upper-crustal rocks. The lower δ¹⁸O values and the observed oxygen isotope disequilibrium between coexisting pyroxenes and amphiboles are explained by interaction with heated meteoric water.