Aim: To determine the prevalence of oral lesions (OL) in patients with psoriasis, and compare these findings with the ones found in patients without this condition. Materials and methods: In the present observational and comparative study, we evaluated 207 patients, with and without psoriasis, attending the dermatological consulting service of a concentration hospital in Mexico City. The possible association between OL and psoriasis was analyzed through a logistic regression model; the Odds Ratio (OR) and its Confidence Interval (CI) was calculated to be 95%. Results: Two hundred and seven cases were examined (80 with psoriasis and 127 without psoriasis). Of these, 75 (36.2%) were men and 132 (63.7%) women. Oral lesions were found in 54 (67.5%) psoriatic patients and in 63 (49.6%) of the comparative group (p <0.012). Fissured tongue (FT) was present in 47.5 % of the patients with psoriasis and in 20.4 % of the group without psoriasis, (OR=3.46, 95% CI [1.14, 10.5], p=0.001). Geographic tongue (GT) was present in 12.5 % of the group with psoriasis and 4.7 % in the group without this disease (OR=3.54 95 % CI [1.97, 6.79], p=0.028). Likewise, six patients (7.5 %) with psoriasis and 3 (2.36 %) from the comparative group presented simultaneously GT and FT (p = 0.0776). The most frequent type of psoriasis was the vulgar psoriasis (90 %), in which a higher prevalence of FT (p <0.05) was present. There were no differences between both groups (p>0.05) regarding the use of tobacco. Alcohol consumption was greater (55.0%) among patients with psoriasis than among those without psoriasis (26.7%) (p<0.05), but when the association with GT and FT was analyzed, no significant differences were found among consumers and not consumers of tobacco and alcohol (p> 0.05). Conclusions: The high prevalence of GT and FT in patients with psoriasis suggests that these lesions should be taken into account in new studies as possible predictors or markers of the severity of this dermatosis, in order to confirm the association of these entities.