Requests are quite often received for information about methods of marking bees—whether for locating the queen, for distinguishing bees of a certain group (e.g. age) from others in the colony, or for distinguishing bees of one specific colony from other bees. In this article Professor Smith, of the Apiculture Department (now part of the new Department of Environmental Biology) at the University of Guelph in Canada, provides a concise and up-to-date account of methods that have been used successfully, and points out where special caution is needed.