Abstract: - Introduction- Dental class I malocclusion is a most common malocclusion found in north India. Cases with crowding in anterior segment and bimaxillary protrusion is also commonly encountered cases in daily orthodontic practice. The role of mesiodistal width in such malocclusion can be a contributing factor for such malocclusion. Purpose:-the purpose of the study was to determine the correlation between tooth width and type of malocclusion. Methods: 150 pretreatment cast of patients were selected and divided into 3 groups. The mesio distal width of each tooth was measured with Vernier caliper and tabulated. Results: the mesiodistal tooth dimensions of upper and lower anterior tooth were significantly higher in crowded and proclination group than uncrowded group. One-way analysis of variance (ANOVA) was used to compare the mean. Tukey HSD Tests was used for multiple pair wise comparisons of sum of six anterior teeth. Conclusion: There is a significant difference in mesiodistal width of class I patients with anterior crowding or proclination.