AbstractBacterial flagella are appendages used for motility. Their presence is a useful tool for identification and differentiation of prokaryotes. Since flagella are too thin to be seen by compound light microscopy, staining methods employ the use of a mordant (often tannic acid) to make them thick enough to see using an oil immersion objective. Two protocols are described. Basic Protocol 1 is a modified Leifson method and is the one that many microbiologists have adapted. Basic Protocol 2 is a wet‐mount stain using a Ryu stain and is included because the stain is stable at room temperature. Both of these methods are fairly time‐consuming, taking from 15 to as long as 60 min to perform. Curr. Protoc. Microbiol. 15:A.3G.1‐A.3G.5. © 2009 by John Wiley & Sons, Inc.