Chicken Eggyolk Antibodies (IgY) were raised in 22 weeks old white leghorn chicken against formalin killed whole cell antigen of Streptococcus mutans (MTCC No:497). The level of the antibody in serum was monitored and booster doses were given wherever necessary. The antibodies were purified from the eggyolk of immunized chicken using PEG and Ammonium sulphate precipitation method and further purified by DEAE cellulose ion exchange column chromatography. High titre of more than 1:10000 antibodies were detected by Indirect antigen capture ELISA at 150th day of observation. The IgY concentration in egg yolk was increased during the immunization period and reached maximum of 5.8mg/ml. The minimum agglutination concentration of IgY against whole cell antigen of S.mutans was found to be 1:625. Similarly, when pre-immune IgY (control) were used no agglutination were observed. There was a decrease in Streptococcus mutans growth with increasing concentration of antibodies (IgY). The growth was completely inhibited when 25μg/ml of IgY was added to the culture.