N-Carbamoyl-L-amino acid amidohydrolase was purified to homogeneity for the first time from Alcaligenes xylosoxidans. The enzyme showed high affinity toward N-carbamoyl-L-amino acids with long-chain aliphatic or aromatic substituents, and hydrolyzed those with short-chain substituents quite well. The enzyme hydrolyzed N-formyl- and N-acetylamino acids quickly and very slowly, respectively. The enzyme did not hydrolyze beta-ureidopropionate and ureidosuccinate, The relative molecular mass of the native enzyme was about 135000 and the enzyme consisted of two identical polypeptide chains. The enzyme activity was significantly inhibited by sulfhydryl reagents and required the following divalent metal ions : Mn2+, Ni2+ and Co2+.