Tropical montane cloud forests are characterized by a persistent cloud cover at the vegetation level. In central Veracruz, Mexico, these forests are found distributed in several small fragments with differing degrees of disturbance. In this changing ecosystem, the use of indicator groups has been proposed to assess disturbance effects on biodiversity. Ants may serve as bioindicators in various contexts, as they are social insects that have a high response capacity to environmental stimuli. In this study, the relationship of several environmental characteristics to ant diversity was measured in 5 fragments of tropical montane cloud forest in central Veracruz. In total, 5,270 individuals belonging to 75 species, 29 genera, 13 tribes, and 8 subfamilies were collected. The richness, diversity, and evenness increased significantly as a function of the structural complexity of the vegetation. In terms of composition and structure, the assemblages showed high heterogeneity between fragments. The similarity analyses showed high species complementarity between fragments, with a large proportion of unique species to each fragment. A high rate of species turnover is likely due to fragment isolation and its subsequent influence on habitat quality. However, the results demonstrated that overall, the remaining fragments of tropical montane cloud forest sheltered a large ant richness and diversity. In consideration of the observed habitat disturbances, it is necessary to implement measures that would allow for the conservation of the remaining fragments of cloud forest, as they represent an important reservoir of ant species and likely of other organisms as well.