Introduction. Dental caries is a common disease of dental hard tissues and is a major problem among the population. The dental caries errors occur quite frequently, and being not treated in time they can lead to severe complications. Their late detection implies the implementation of contemporary diagnostic methods and the choice of an appropriate treatment tactics.  Aim of the study. To assess scientific literature with reference to possible errors in the diagnosis and treatment of dental caries.  Materials and methods. There were selected and analyzed the clinical cases and X-rays of 25 patients aged 20-50 years, who received dental care at University Clinic of Nicolae Testemitanu State University of Medicine and Pharmacy, in Chisinau. The patients enrolled in the study were subjected to clinical investigations to make the right diagnosis prior to the treatment in order to determine the condition of the dental hard tissues, and to evaluate the treatment performed by the dentist after the investigations.  Results. According to the studied cases, it was found that although the level of dental care is relatively high, with the implementation of multiple modern treatment technologies, in some cases there are a number of errors in the doctors` tactics, resulting in severe complications. Conclusion. The sudy determined that the most common errors were found during the diagnosis, being followed by the errors in preparation and filling methods.