Objective: To investigate the acidogenicity and aciduric ability of Streptococcus mutans isolated from the children with different caries susceptibility.Methods: The acidogenic and aciduric ability of Streptococcus mutans strains isolated from children was investigated.Acidogenicity ability was compared among high caries-susceptible group,middle caries-susceptible group and caries-free group.Results: The acidogenicity and aciduric ability of Streptococcus mutans isolated from the high caries-susceptible children and middle caries-susceptible group were significantly higher than that isolated from caries-free group(P