The use of a particular language as medium of instruction (MOI) is a complex issue in multilingual and post-colonial contexts such as Hong Kong, on which teachers’ voices are often neglected. To capture their voices, this paper reports on an interpretive inquiry of eight experienced Chinese teachers’ professional experiences with a focus on their perceptions concerning the increasing use of Putonghua as MOI in Chinese classes in Hong Kong. Through a collaborative interpretative process, the study revealed a wide spectrum of perceptions including reservations and enthusiasm for the switch to Putonghua as MOI. The findings suggest that the participants’ perceptions could be explained by references to shifting political, demographical conditions, the participants’ experiences of curriculum reforms and their concerns with pedagogical conditions. The paper ends with a discussion for the study’s implications for Chinese language teacher education in Hong Kong and elsewhere. Copyright © 2010 Edith Cowan University.