This report describes the inhibition of spore germination by N-acetylmuramic acid. At concentrations of 20 mM and higher, the rate of germination of the treated spores was ten-fold lower than that of the control spores. The inhibitor also depressed the activity of two germination-related enzymes; a coat-associated hexosaminidase and a core enzyme. These findings suggests that N-acetylmuramic acid affects spore germination by inhibition of the corticolytic enzymes. The results are discussed with respect to the possible role of these enzymes in germination.