The Biological Stain Commission is an organization certifying scientific stains. The BSC is a 93-year-old organization well known to many thousands of scientists, worldwide but especially in N America, who buy certified dyes for staining of microscopic preparations or for making up selective culture media for bacteria. Manufacturers and other vendors submit samples from their batches of dyes to the BSC's independent laboratory in Rochester NY. The BSC's certification label on a bottle of dye indicates that the contents are from a batch that passed the tests for chemical purity and for efficacy as a biological stain. These tests are published (Penney et al. 2002a). Changes to tests and additions to the list of stains eligible for certification are published from time to time in Biotechnic & Histochemistry and are summarized on the Commission's web site.