Purpose: To determine the most and least attractive smiles from a Brazilian sample and to correlate the anatomical characteristics identified in these smiles. Materials and methods: Orthodontists, dentists, and laypeople assessed the photographs of 86 students (66 women and 20 men), aged between 19 and 30 years, using a visual analog scale (VAS). An evaluator blinded to the results measured the esthetic composition of the eight photographs with the highest and the eight with the lowest ratings for women, and the two with the highest and the two with the lowest ratings for men. The mean and standard deviations were calculated for the descriptive analysis. Results: A total of 42 anatomical smile details were identified and described, obtaining the means of the characteristics. Conclusions: The following characteristics were observed from the selected most attractive smiles: parallel smile arc, oval-shaped incisors with square-rounded edges, increase of the incisal embrasure and reduction of connector space in distal progression, display of maxillary incisors and minimum display of mandibular teeth, gingival margin of central incisors 0.5 mm coronal to the canines and 0.8 mm apical to the lateral incisors, posterior gingival display of 1.5 mm, less than 20% of buccal corridor and display of 12 teeth, and canines with -2 degrees of inclination. The most attractive smiles also had an absence of asymmetries, diastemas, black spaces, incisal plane inclination, and anterior gingival display.