Addition of 1–2 mM sodium fluoride (NaF) to complex growth medium caused a pronounced decrease in the incorporation of 3H-glycerol into cellular and extracellular lipoteichoic acid (LTA) by Streptococcus mutans, strain BHT. Cell yield and the final pH of the culture were not significantly affected by these levels of NaF. Similarly, the extracellular concentrations of polymer-derived glycerol were not affected. Radioactivity incorporated into cells from a 14C-protein hydrolysate was not influenced by NaF even at a concentration of 10 mM NaF where the cell yield was decreased by 43%. The results suggest that low concentrations of fluoride inhibit incorporation of exogenously added glycerol into LTA of S. mutans, strain BH