Abstract: The micronucleus test with the erythrocytes of the Misgurnus Anguillicaudatus was adopted to study the mutagenic activity of wastewater from pig farms.The results showed that the micro-and anomalous nuclear rates significantly increased after 2 days of treatment,peaked on the 5th day,and declined a afterward.In another experiment where varying concentrations of the wastewater were used,the rates increased with a significant dosage-dependency.The differences between the tests and the control were very significant,indicating that pig farm wastewater was mutagenic to a certain degree.