The volatile compounds present in the volatile oils and aroma from fresh flowers of Bidens segetum Martius ex Colla were characterized. The samples were collected from naturally occurring populations of the Brazilian Cerrado and from plants cultivated at the Instituto de Botânica de São Paulo (Atlantic rainforest) from its seeds. The essential oils were obtained by hydrodistillation in a Clevenger apparatus, while the aroma was extracted by headspace solid-phase microextraction (HS-SPME) and both were analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS). β-Phellandrene (18-45%) and germacrene D (6-32%) were always present in the oils and aroma; however, their percentages varied. Besides these, E-β-ocimene (11.6%), myrcene (11.2%), α-pinene (7.3%), sabinene (6.7%), bicyclogermacrene (5.7%) and δ-cadinene (3.2%) appeared as major constituents of the volatile components from B. segetum flowers.