Abstract: The Sm–Nd isotope ages of apoamphibolite eclogites and eclogite-like garnet-clinopyroxene crystalline schists collected in the Chupa and Engozero segments of the Belomorian mobile belt are estimated. Eclogites and eclogite-like garnet–clinopyroxene rocks demonstrated nearly the same isotope age (2119 ± 170 and 2191 ± 39 Ma, respectively) on the same pair of minerals (garnet–clinopyroxene). The age obtained (about 2.1 Ga) is the oldest indicator of the onset of Paleoproterozoic metamorphism in the Belomorian mobile belt.