Wnt10b (wingless-related mouse mammary tumour virus integration site 10b) plays various roles in a wide range of biological actions, including hair-follicle development. To assess the roles that Wnt10b plays in postnatal hair-follicle growth. Adenovirus vectors AdWnt10b, AdGFP, AdGFP plus AdRFP, AdWnt10b plus AdFrzB, and AdWnt10b plus AdSimBC were co-cultured separately with vibrissae. In situ protein expression of Wnt10b, β-catenin and Lef1 was determined by immunohistochemistry, and the proliferation status of the hair follicle was detected by 5-bromo-2-deoxyuridine (BrdU) labelling. The presence of Wnt signalling molecules in the three stages of hair-follicle growth was detected by PCR-based microarray. AdWnt10b-infected cells were able to secrete bioactive Wnt10b, and when this was added into the basal medium, the vibrissae grew faster than in control medium or in medium containing canonical Wnt signalling antagonists. The in situ protein expression of Wnt10b was consistent with that of β-catenin and Lef1. The expression locus of Wnt10b was almost the same as the proliferating cells labelled by BrdU in the anagen hair follicle. Wnt10b may promote hair-follicle growth by inducing the switch from telogen to anagen via a canonical Wnt signalling pathway to promote the proliferation of matrix cells. © The Author(s). CED © 2011 British Association of Dermatologists.