To clinicopathologically characterize the diagnosis of oral lichenoid disease (OLD) and its main subtypes: oral lichen planus (OLP) and oral lichenoid lesion (OLL), in order to correctly asses their prognosis. Ambispective cohort study of 384 patients with diagnosis of OLD, based on pre-established clinical and histopathological criteria. We have analysed 272 (70.8%) women and 112 (29.2%), whose mean age was 57.1+/-11.8 years (range 21-90); minimum follow-up time was 36 months. A specific protocol was designed for this study, where we gathered the data of each patient, including malignant transformation. OLP was diagnosed in 229 cases (77.9%) and OLL in 85 (22.1%). Tobacco consumption was found in 20.3% of the patients and alcohol intake in 41.1%. Liver pathology was present in 10.7% of the cases, thyroid pathology in 11.5%, arterial hypertension in 15.6%, diabetes mellitus in 7.6%, psycho-emotional disorders in 33.3%, skin involvement in 12% and genital involvement in 4.9%. Ten patients (2.6%) developed an oral squamous cell carcinoma, 5 (1.7%) with OLP and 5 (5.9%) with OLL. OLD is a potentially malignant disorder of the oral mucosa which has to be correctly diagnosed as either OLP or OLL, since the risk of malignancy of these subtypes is significantly different.