In order to evaluate the difference between plaque reduction neutralization test (PNt) and hemagglutination inhibition (HI) test on human anti-measles antibodies, pre- and postimmunization sera collected from 328 infants aged 3-6 months who were immunized with Shanghai 191 measles vaccine, were detected by both methods. The results demonstrated that PNt was more sensitive than HI when they were used to measure the pre-immunization sera. No significant difference was found between these two methods when they were used to measure the post-immunization sera. PNt can be used to test low level maternal anti-measles antibodies in infants, especially for estimating the effect of maternal anti-measles antibodies on the immunogenicity of measles vaccine.