Salivary innate defenses encompass mechanical cleaning, calcium phosphate salts and fluoride ion reduction of enamel dissolution rate, buffering capacity and neutralizing capacity, and antibacterial properties employing antimicrobial substances like antimicrobial peptides,agglutins,lactoferrin, lactoperoxidase, lysozyme and immuno globulins. Antimicrobial peptides play a key role in the initial defensive responses that make up innate immunity. The aim of this study was to assess the relationship between salivary physicochemical characteristics like buffering capacity, pH, flow rate, and concentrations antimicrobial human peptide like HBD-3, HNP1-3 and LL-37 and caries activity in young children. Before to collecting the samples, informed permission papers were gathered and completed by the children's legal guardians or parents. There was significant correlation showing reduced caries activity on increased concentrations of HNP1-3. When there was analysis of correlation of CAS with LL-37 concentrations then the p value vas 0.002 showing the correlation was significant. There is significant relationship between salivary physicochemical characteristics like buffering capacity, pH, flow rate, and concentrations antimicrobial human peptide like HBD-3, HNP1-3 and LL-37 and caries activity in young children.