The purpose of the present study was to assess the success of root canal treatment in permanent molars of children and adolescents. Twenty-eight endodontically treated first permanent molars of 18 patients aged 8 to 16 years at the time of treatment were examined. The age of the patient at the time of treatment ranged from 8 to 16 years (mean age 12.4 +/- 2.3). The majority of the treatments were done on the mandibular teeth (67%). Nine patients had one treated molar, eight patients had two treated molars and one patient had three treated teeth. None of the patients had all four molars treated. The time elapsed from the root canal treatment until our examination ranged from 24 months to 77 months (mean time 45.1 +/- 19.1). The examination included clinical and radiological parameters as follows: sensitivity to percussion, mobility, quality of restoration (contact point reproduced, overhang, secondary caries), periapical lesions before and after treatment, external root resorption, furcation involvement and interproximal bone resorption. Treatment was considered completely successful if no pathology was found. Only 10 teeth (36%) demonstrated complete treatment success, less than previously reported. No significant differences between mandibular and maxillary teeth were found with respect to any of the variables. The results suggest that considering a number of multidisciplinary criteria for assessing success of root canal treatments in first permanent molars of children and young adolescents is essential, and provides a realistic success rate.