The crude extract and the hexane, CH2Cl2, EtOAc, n-BuOH, and hydromethanolic fractions of the aerial parts of Mitracarpus frigidus were evaluated against promastigote forms of two species of Leishmania (L. chagasi and L. amazonensis), 11 strains of bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica sorovar Tythimurium, Shigella sonnei, Klebsiella pneumoniae, Escherichia coli, Micrococcus luteus, Enterococcus faecalis, Enterobacter cloacae, Streptococcus pyogenes and Bacillus cereus) and two yeasts (Candida albicans and Cryptococcus neoformans). The antioxidant activity (DPPH radical scavenging activity and reducing power), cytotoxicity against mammalian cells, and the contents of phenolics and flavonoids were determined. Phytochemical analysis of the major groups of phytoconstituents is also reported. All samples showed antioxidant activity which was positively correlated to the content of phenolic compounds. S. sonnei, B. cereus and C neoformans were susceptible to all extracts tested, except for the n-BuOH and hydromethanolic fractions, which demonstrated no antimicrobial activity. The lowest MIC was recorded for the CH2Cl2 fraction against C neoformans (MIC of 10 mu g/ml), followed by B. cereus, S. sonnei, and E. cloacae (MIC of 20, 39 and 39 mu g/ml, respectively). The CH2Cl2 fraction was the most effective against L. chagasi (IC50 of 6.7 mu g/ml), and the hydromethanolic fraction exhibited the best activity against L. amazonensis (IC50 of 9 mu g/ml). A cytotoxic effect on mammalian cells was observed only for the crude extract and CH2Cl2 fraction at the concentrations of 130 and 31 mu g/ml, respectively. These results suggest that M. frigidus has interesting antimicrobial, antileishmanial and antioxidant activities. (C) 2008 Elsevier Ltd. All rights reserved.