Introduction: An attractive smile helps people feel more self-confident and look younger. One of the more controversial aspects of smile attractiveness pertains to buccal corridor size. There is no previous study by those with artistic knowledge that has assessed the esthetic considerations of buccal corridor size. The purpose of this study was to observe whether the size of buccal corridors has an impact on smile attractiveness evaluated by lay people, dental students, and art students. Materials and Methods: Colored posttreatment photographs with posed smiles of two subjects (one male, one female) were selected. The maxillary posterior dentitions were digitally altered to produce different buccal corridor sizes: narrow (28% buccal corridor), mediumnarrow (22% buccal corridor), medium (15% buccal corridor), medium-broad (10% buccal corridor), and broad (2% buccal corridor). The 5 images of each subject were paired into 11 possible combinations and presented to three groups: art students, dental students, and lay people, who compared the two images in each pair for smile attractiveness. The statistical tests used were Wilcoxon signed rank test and Mann- Whitney test. Results: Minimal and excessive buccal corridors were the least attractive when judged by three groups. All groups preferred smaller buccal corridors for the male subject and larger buccal corridors for the female subject. No significant judging differences were found between male and female judges from among art and dental students. Conclusions: Minimal or excessive buccal corridors should be included in the problem list during orthodontic diagnosis and treatment planning.