Between 1996 and 2000, a probable Common Guillemot Uria aalge x Razorbill Alca torda hybrid was observed periodically among breeding Common Guillemots on Great Island. Newfoundland, Canada. Although the overall body shape and size of this individual were comparable to those of a Common Guillemot, it possessed traits that appeared intermediate between the Common Guillemot and the Razorbill. We suggest that hybridisation between these two auks may occur, albeit rarely, as a consequence of their extensive overlap in breeding range and close proximity within breeding colonies.