BACKGROUND: The aim of this study was to investigate the caries risk of asthmatics in relation to dental plaque indices, salivary flow rate, pH and buffer capacity, saliva composition and salivary levels of Streptococcus mutans compared with healthy subjects and also to evaluate these parameters within different groups of asthmatics according to their medication, duration and severity of the disease. METHODS: The study group composed of 106 asthmatics and 100 healthy controls with the same age and social background aged between 6 and 19-years-old. For dental examinations, World Health Organization criteria and for plaque indices the Silness and Löe plaque index was used. All data were analyzed using t-test, chi2-test, Spearman rank correlation, Kruskal- Wallis, Mann-Whitney U-tests and Logistic Regression Analysis with Forward Stepwise Likelihood ratio method. RESULTS: A statistically significant decrease in the salivary flow rate and pH were found in the asthmatic group. The children in the asthmatic group aged between 6 and 10 years had significantly higher caries prevalence compared with the control group at the same age. There was a negative correlation between the duration of medication and the salivary pH and a positive correlation between duration of illness and the salivary levels of S. mutans in the asthmatics. CONCLUSION: It was found that asthma, through its disease status and its pharmacotherapy, carries some risk factors including decreased salivary flow rate and pH for caries development. It was also demonstrated that the duration of medication and illness had significant influences on the risk of caries in asthmatics.