Introduction: The aim of this study was to revising and presenting results of in vitro studies referring to the precision of the dimensions of orthodontic brackets’ slots. Materials and methods: Search was proceeded for studies describing results of measurements of the dimensions of orthodontic brackets slots performed with the use of various available measuring instruments. Brackets from various manufacturers were taken into consideration. Search was performed in Pub-Med and Google Scholar. The following keywords were used: „bracket slot”, „orthodontic bracket slot dimension”. Studies were included, if they based on two separate measurements: at the slot opening and along the slot bottom. Studies were rejected if they described an analysis of bracket slot structure or roughness without providing slot dimensions. Results: Finally, 13 papers were selected from PubMed and 9 papers – from Google Scholar (all the papers from PubMed were found in Google Scholar as well). All the studies analysed, regardless of the method of measurement and material used for the manufacturing of orthodontic brackets revealed, that slot dimensions were higher or lower than the declared standard size. Moreover, analysis of slot appearance provided interesting information pertaining to the shape of bracket slots, e.g. parallelism, convergence or divergence of their walls. Conclusions: Basing on the review it can be stated that orthodontic brackets are characterized by imperfections that may characterize single brackets, bracket sets or series. They may potentially influence the process of three-dimensional aligning of individual teeth during orthodontic treatment.