Aloe vera L., popularly known in Brazil as “babosa”, has great pharmacognostic value and is widely used in folk medicine. Numerous properties have been identified in extracts of this plant, such asantioxidant, antitumor, antidiabetic, antibiotic, anti-inflammatory, and immunostimulatory activities. We aimed to evaluate the effect of Aloe vera commercial juice on the development of normal and mutant strains of Aspergillus (= Emericella) nidulans and on antimutagenesis in the methG1 system of this fungus; as well as its genotoxicity on Wistar rats, evaluated through the comet assay. In both germination and antimutagenicity assays, two juice concentrations (4% and 8%, v/v) were tested. Animals were treated for 7 days with juice at concentratio...