The purification and properties of N-acyl-D-glutamate deacylase from the cell extracts of Alcaligenes xylosoxydans subsp. xylosoxydans A-6 were studied. The two active fractions (peaks I and II) were obtained by a Mono Q column chromatography. The predominant enzyme (peak I) has been purified, 1960-fold to homogeneity and characterized. The enzyme was a monomer with a molecular weight of 59 000. The optimum pH and the isoelectric point were 8.0 and 5.5, respectively. The enzyme catalyzed the hydrolysis of N-acyl derivatives of D-glutamate. The K m s for N-acetyl, N-butyryl and N-propionyl derivatives of D-glutamate were 0.129, 0.066 and 0.01 mM, respectively.