The purpose of the experiment is to evaluate whether pentacyclic triterpeneds extracts as a feed additive has potential mutagenicity through Ames test, micronucleus test and sperm deformity test. In Ames test, substance dose groups were set as 0.008, 0.040, 0.200, 1.000 and 5.000 mg/dish. Negative control (steriled water, DMSO) and positive control groups were set. Each treatment was set with two series of metabolic activation system (+S9) and non metabolic activation system (-S9), determining the number of returning mutant colonies of test bacteria. In the micronucleus test, the dose groups of test substance were set as 1.25, 2.50 and 5.00 g/kg by gavage, and the positive control (cyclophosphamide) and negative control (1% carboxymethyl cellulose solution) were set up. The micronucleus rate of mouse bone marrow cells was measured at an interval of 24 h after twice administration. In the sperm deformity test, the dose groups of test substance were set as 1.25, 2.50 and 5.00 g/kg by gavage, and the positive control (cyclophosphamide) and negative control (1% carboxymethyl cellulose solution) were set up. The interval was 24 h for each of the five times of administration. The mice were killed 35 d after the first administration, and the sperm abnormality rate and types were counted. Compared with the control group, the average number of retrogressive colonies in Ame experiment was less than twice that in solvent group, and there was no dose-response relationship. The micronucleus rate of bone marrow and sperm aberration rate had no significant effect (P>0.05). Mutagenic test results were all negative. The results shows that pentacyclic triterpenoids exhibits no mutagenic effect. [ABSTRACT FROM AUTHOR]