U–Pb dates on three fractions of zircon from the foliated border zone of the southeast part of the Kuskanax batholith are slightly discordant and indicate emplacement of the batholith ago, assuming no subsequent zircon Pb loss. The analyses are slightly discordant and reflect the presence of inherited zircon Pb ~2060 ± 300 Ma old. This interpretation of the data is consistent with geological relationships and available K–Ar dates. A geologically derived maximum age for the batholith is about 185 Ma. This age determination has important implications for timing of deformation in the Kootenay Arc.