Objective: Morphometric study of the dorsum linguae in patients with Oral Lichen Planus (OLP).Material and Method: In 236 patients with a clinicopathologic diagnosis of OLP, 111 were found to have involvement of the dorsum linguae. For the purposes of the study, 41 of these cases were used, due to the availability of photographic records fulfilling quality conditions according to objective criteria. The experimental variable was defined as the proportion of affected dorsum linguae measured and calculated using the MIP4(R) computer software.Results: In 236 patients with OLP, the mucosa of the dorsum linguae was affected in 47.6% of the cases (total 111). The proportion of affected area was studied in 41 of these cases, 8 men (19.5%) and 33 women (80.5%). In 73% of these cases, the affected area was less than 50% of the total surface of the dorsum linguae. There were no statistically significant differences (p=0.495) in relation to age and proportion of lingual surface affected. On the other hand, significant statistical differences were found between the period of disease evolution and area of lingual involvement (p=0.044).Conclusion: Lingual involvement is frequent in patients with OLP, and manifests as de-papillate areas to the left and right of the median sulcus of tongue (occasionally linked by an isthmus) and having a certain “ butterfly wing” symmetry