Background and Aims: The dentist's attire and appearance affects his/her relationships with the patients. It is also essential to sync the PROFESSIONAL attire in dentistry with the habits and Islamic culture of Islamic Republic of Iran, meet the patients' desires, and pay attention to the infection-control-requirements as well. The objective of the present study was to determine the patients' viewpoints about the PROFESSIONAL appearance of the dentists at Tehran University of Medical Sciences, Dental School in 1395-96. Materials and Methods: In this descriptive cross-sectional study, 103 patients (54 females and 49 males) were studied. (α =0. 05 and standard variation=4. 5). The questionnaire were included color photographies of a female dentist and a male dentist dressed in different attires. The patients were asked to select the cleanest, and the most trustable, competent, and experienced dentist according to the 4 different attires. The frequencies and percentages of the participants’ answers to the questionaire were descriptively reported. Results: All patients preferred dentists to use white coat during their treatment. For the male dentists, most patients (45. 6%) favored simple hair model. For the female dentists, most patients (35. 9%) considered veil as the more acceptable Hejaband, and 54. 4% of them preferred light makeup. Conclusion: All patients preferred their dentists to dress in the PROFESSIONAL attire with a white coat. They believed that wearing formal-PROFESSIONAL-dressing by the dentists may show them look cleaner, and more trustable, more competent, and experienced.