Understanding of the size effect on shear banding in bulk metallic glasses (BMGs) is currently the topic of active research but also remains under intense debates. In this article, we provide an overview of the recent research findings from experiments, theoretical modeling, and atomistic/continuum simulations which are intended to advance our knowledge related to the size effect on the stability of shear-band propagation in BMGs. Through the compilation of and comparison among the results reported in the literature, we aim at providing a comprehensive understanding of the underlying mechanisms and a unified physical picture of the size effect on shear-band propagation and its resultant ductility in BMGs.