The aim of the study was to establish the colonization of Streptococcus mutons and to determine the possibility of intra-familial transmission in a group of Turkish children and their parents. A total of 56 children participated in the study together with their parents (20 fathers and 49 mothers). Saliva samples were collected from the individuals and cultivated on S. mutans selective TYCSB agar. The typical isolates of S. mutans were identified by using classical. microbiological methods, as well as molecular typing of S. mutans clones. which was performed by using AP PCR with OPA5 primer for the detection of transmission. The vertical transmission of salivary S. mutans was detected among 14 mother-father-child, 35 mother-child (one twins) and 6 father-child combinations. The homologies of strain types were recorded as 24% and 16.6% for mother-child and father-child combinations, respectively. A significant positive correlation (p<0.001) was found between the infected children and their parents with high S. mutans counts. (C) 2006 Elsevier GmbH. All rights reserved.