Abstract: Callus cultures were established on callus derived from stems of young Kyaraboku (Taxus cuspidata Sieb. et Zucc. var. nana) trees and the effect of oligosaccharides on taxol production was investigated. The production was stimulated about 5.1-fold and 1.2-fold by the addition of chito-oligosaccharides (COS) and laminaran-oligosaccharides (LOS), respectively. To find the active compound that stimulates the taxol production, COS were separated into 8 fractions (Fr.1 - Fr.8) by ion-exchange chromatography. Fr.5 was found to be the most active fraction and chitoheptaose was its most active compound. The production was stimulated 8.2-fold on addition of chitoheptaose to the calli.