The aim of this study was to evaluate the in vitro antioxidant and cytotoxic activities of the methanolic extract and fractions of Senecio gibbosus subsp. gibbosus aerial parts. The antioxidant activity was assessed by means of two different tests: (1) bleaching of the stable 2,2-diphenyl-1-picrylhydrazil (DPPH) radical; and (2) lipid peroxidation of liposomes which were prepared from bovine brain extract. In both tests used methanolic extract and AcOEt fraction showed a significant antioxidant effect. The cytotoxic activity of the methanolic extract and fractions was carried out using the SRB assay. The methanolic extract demonstrated a good cytotoxic activity against human breast cancer cell line (MCF-7) and human prostate cancer cell line (LNCaP). Dichloromethane and AcOEt fractions showed the greatest cytotoxic activity, particularly on LNCaP cell line.