Abstract: The results of 190Pt–4He dating of placer-forming minerals of platinum (PMP) from the Baimka gold placer cluster (Western Chukotka, Russia) are reported. PMPs are represented by isoferroplatinum with a composition of Pt3 + xFe1 – x and Pt3Fe. The concentrations of 190Pt and 4He in 14 PMP samples were obtained. The results of 190Pt–4He dating showed the existence of two age clusters of PMP (148 ± 6 and 188 ± 4 Ma) for the first time. The primary sources of PMP, which are similar in their genetic type, but have different ages, are assumed: (1) later, 148 ± 6 Ma of the Baimka Complex (J3b) and (2) earlier, 188 ± 4 Ma. PMPs enter alluvial gold placers mainly from the intermediate PGM reservoir, which is composed of rocks of the Volgian stage J3v2–3 (Tithonian). Thus, sedimentary rocks or explosive breccia of andesite–basalt of the Volgian stage could be the PMP source reservoir.