The analysis method and stability test of antineoplaston A10, a new anticancer drug candidate, were established. A10 and phenylacetyl-L-glutamine, one of the degradation products, can be detected by high-performance liquid chromatography. The degradation kinetics of antineoplaston A10 in aqueous solutions from pH 1 to 10 buffers were carried out at 40, 50 and 60 degrees C. Pseudo-first order kinetics were obtained throughout the entire pH ranges studied. The pH-rate profiles showed that antineoplaston A10 was very unstable in alkaline conditions and most stable at pH 4.