Lianas are abundant and diverse organisms in tropical forests. Their increase is strongly associated with the occurrence of forest disturbances that affect forest dynamics in a negative way. Fire-induced disturbances are likely to increase in the scenario caused by climate change in which extreme droughts become more and more frequent due to the increase in the planet's average temperature. The objective was to answer the following questions: (i) What is the density and diversity of lianas in a fragment of semideciduous seasonal forest? (ii) Is there a difference in infestation (composition, density, diversity, and structure) of lianas in a disturbed area with and without forest fire occurrence? The study was carried out in a semideciduous forest fragment with (A1) and without (A2) occurrence of forest fire. The lianas, which were ascending to the canopy, were measured in a census-type inventory with a minimum inclusion diameter of 1.0 cm, 1.30 m from the main rooting point, with a precision digital tree caliper. Trees were also measured in a census-type inventory, with a minimum diameter at breast height (DBH) of 5.0 cm, using a tape measure. The height of all trees was measured with the Vertex & REG; device. The Kolmogorov-Smirnov (K-S) test of adherence, at 5% probability, was applied to check whether the diametric distribution of lianas differed statistically. Fire altered the species composition of lianas by 36%. The density of lianas increased after the forest fire occurred, by 65%. Fire altered the diametric distribution of lianescent individuals and acted as a homogenizing agent of species composition, removing sensitive species and increasing the abundance of species tolerant to it. The increase in density was favored by the light conditions provided by the opening of the canopy after the forest fire occurred. Fire altered the diametric distribution of the lianas which differed statistically by the K-S adherence test at 5% probability. Fire alters the species composition and structure of liana individuals, increases the density and decreases the diversity of lianas in a fragment of semideciduous seasonal forest with Araucaria angustifolia.& COPY; 2023 SAAB. Published by Elsevier B.V. All rights reserved.