A new biochemical method for more efficient production of N-a-benzyloxycarbonyl-L-aminoadipate 8-semialdehyde (N-a-Z-L-AASA) and N-a-Z-D-AASA was developed with cells of Rhodococcus sp. AIU Z-35-1. Using the cells harvested after 1 d of cultivation, more than 95 mM N-a-Z-L-AASA was produced from 100 MM N-a-Z-L-lysine by incubating at pH 5.0 for 1 d at 30 degrees C or by incubating at pH 7.0 for 2 d at 10 degrees C. A similar conversion yield of N-a-Z-D-AASA was also obtained under the same conditions. These reaction times required were 1/4 and 1/2 of the respective ones by the method with amine oxidase, and the yields of N-a-Z-L-AASA and N-a-Z-D-AASA were 2 times higher than the respective ones by the method with amine oxidase. In addition, this method had the advantages of not requiring purification of enzyme and addition of catalase. Thus, the microbial method proposed here was superior to the chemical and other biochemical methods in simplicity, reaction rate, and yield.