BACKGROUND There has been an ongoing controversy as to the best dilution for botulinum toxin for use in cosmetic applications. Recommended dilutions have ranged from 1 ml per vial to 10 ml per vial. There has also been much discussion on the diluent, i.e., preserved versus unpreserved saline, to be used and on storage time of the material after dilution. OBJECTIVE The objective of this paper is to examine the literature and experience of practitioners in the field to try to resolve some of the questions concerning dilution and storage of botulinum toxin. CONCLUSIONS Although there is great variation in the dilutions adopted by various physicians, much of this is a matter of personal preference. It does seem to appear that most clinicians use a dilution near 2.5 to 3.0 ml per vial and three-quarters of them limit the storage of the diluted product to 1 week or less.