Objective: The objectives of this clinical study were to: evaluate the survival of occlusal atraumatic restorative treatment (ART) restorations, on a longitudinal basis, in the primary molars of children; and compare the success rate of ART restorations placed in school environment and in hospital dental setup.Study design: One dentist placed 120 ART restorations in 60 five- to seven year-olds who had bilateral matched pairs of carious primary molars. A split-mouth design was used to place restorations in school and in hospital dental setup, which were assigned randomly to contralateral sides. Restorations were evaluated after 6 and 12 months using the ART criteria. Results: The survival rate of ART restorations placed in school environment was 82.2% at the 6-month assessment and 77.77% at the 12-month assessment. The success rates of ART restorations placed in hospital dental setup in the 2 assessments were 87.7% and 81.48%, respectively. There was no statistically significant difference between the ART restorations placed in school environment and hospital dental setup in both assessments (P>O.05). The main cause of failure was the loss of restoration. Conclusions: The one year success rate of occlusal ART restorations in primary molars was moderately successful. The ART technique's done in hospital dental setup was not proven to be better than restorations placed in school environment. © Medicina Oral S. L.