The ages of Mesozoic volcanic rocks in Zhejiang Province have been controversial for a long time. The major divergence lies in whether they belong to the late Jurassic, early Cretaceous or late Cretaceous. Lapierre et al. (1997) concluded on the basis of two Rb-Sr isochron ages that the Jiande Group volcanism (124 Ma) in western Zhejiang should be grouped into the first mag-matic event of Episode I , the Moshishan Group volcanism (97 Ma) in eastern Zhejiang into the second magmatic event of Episode I ,and the Yongkang Group volcanism (<97 Ma) in eastern Zhejiang into Episode I . Based on plentiful isotopic dating data and geological studies, the authors , in this paper, discuss the geological meanings of the two isotopic ages given by Lapierre et al. , and conclude; (1) Mesozoic volcanic activities in Zhejiang are most frequent in 130-83 Ma, that is, from the early to late Cretaceous but not the late Jurassic; (2) The Jiande and Moshishan groups are nearly in the same period and not in an upper-lower stratigraphic relationship with each other;(3) The period of 110-100 Ma is a transitional stage from the early high-K calc-alka-line dacite-rhyolite (associated with diorite-granodiorite) to the late basalt-rhyolite(associated with K-feldspar granite-alkali granite).