Background: Microdontia is a condition where the teeth are smaller than the normal size, which may involve all teeth or be limited to a single tooth or a group of teeth. The objective of this study was to find out the prevalence of microdontia among orthodontic patients of Kathmandu, Nepal. Methods: In this cross-sectional study, 190 orthodontic casts of patients (166 males and 224 females) who came for orthodontic treatment between the age of 14 to 28 years (mean age of 17.43±4.28 years) were randomly selected. The mesiodistal dimension of each tooth was recorded with the help of digital vernier caliper. A tooth was diagnosed as microdontia when it is smaller than the normal size. Data analysis was performed using SPSS version 21.0 with a confidence level set at 95% (P<0.05). Chi-square test was used to determine the difference in prevalence of microdontia among the genders. Whereas, mesio-distal dimensions of teeth were compared on both sides of the jaws using student’s t-test. Results: The prevalence of overall microdontia was 6.66% (26) whereas prevalence of single tooth microdontia, multiple teeth and generalized microdontia was 2.3% (9), 2.83% (11) and 1.53% (6) respectively. There was no statistical difference in the prevalence of microdontia among genders (p=0.987). In addition, there was no statistical difference in the mesio-distal dimensions of teeth on both sides of the jaws (p>0.05). Conclusion: The most common tooth affected by microdontia was maxillary lateral incisor. There was no statistically significant difference in prevalence of microdontia among genders. Keywords: Microdontia, Nepal, Orthodontic patients, Prevalence