Roots of Galianthe thalictroides K. Schum. (Rubiaceae) are used in folk medicine in the State of Mato Grosso do Sul, Brazil, for treating and preventing cancer.To gain information about the genotoxicity of extracts (aqueous and EtOH), the CHCl3 phase resulting from partition of the EtOH extract and the indole monoterpene alkaloid 1 obtained from this plant. The genotoxicity of 1 and extracts was evaluated in vivo through the Drosophila melanogaster wing Somatic Mutation and Recombination Test - SMART, while in vitro cytotoxic (MTT) and Comet assays were performed only with alkaloid 1. The results obtained with the SMART test indicated that the aqueous extract had no genotoxic activity. The EtOH extract was not genotoxic to ST descendants but genotoxic to HB ones. The CHCl3 phase was genotoxic and cytotoxic. Alkaloid 1 showed significant mutational events with SMART, in the cytotoxicity assay (MTT), it showed a high cytotoxicity for human hepatoma cells (HepG2), whereas for the Comet assay, not showing genotoxic activity. The ethanol extract was shown to be genotoxic to HB descendants in the SMART assay, while the results obtained in this test for the monoterpene indole alkaloid 1 isolated from this extract.