In the present work the antioxidant and antimycobacterial activities were determined for extracts from Tabernaemontana catharinensis. The extracts' global yields were obtained using supercritical CO2 plus cosolvent. The cosolvents ethanol, isopropyl alcohol, methanol, and water and their mixtures were used. The extracts were fractionated and analyzed by thin-layer chromatography and gas chromatography/flame ionization detection. The antimycobacterial activity was measured against Mycobacterium tuberculosis, Mycobacterium avium, and Mycobacterium kansasii. The antioxidant activity was determined by the coupled reaction of beta-carotene and limonene acid. The average global yield was approximately constant (2.4 +/- 0.1%) for the alcoholic cosolvents and significantly larger (15 +/- 1%) for the cosolvent water and its alcoholic mixtures. The content of alkaloids in the extracts was strongly affected by the cosolvent. The antioxidant activity of the extracts ranged from 53% to 95%. The highest antimycobacterial activity was detected in the alkaloidal fraction (minimum inhibitory concentration = 128 microg/mL), while the lowest was verified in the aqueous fraction (minimum inhibitory concentration >512 microg/mL).