K-Ar age determinations were carried out on ten specimens from seven representative gold deposits in South Korea. Microclines separated from pegmatites, which are associated with gold alaskite vein in the Geumjeong mine, yield ages of late Proterozoic. White micas in ores and associated pegmatites from the Homi, Cheonbo and Namchang mines in the Cheonan district, give ages of 130-160Ma, and confirm the middle to latest Jurassic gold mineralization in this district. The results for sericites from the Mugug, Imcheon and Geochang mines are around 100Ma. The present results together with data available in the literature reveal that majority of precious, base and heavy metal deposits at the present erosional levels in South Korea were formed in Cretaceous time with a genetic relationship to the Bulgugsa felsic igneous activity.