abstract the volatiles of ageratum conyzoides collected at the municipality of santar'em novo (samples a, b and c), and bel'em (sample d), state of par'a (north of brazil), were obtained by hydrodistillation and analyzed by gc-fid and gc-ms. the inflorescence, leaf, stem and root oils of the sample a were dominated by precocene i (inflorescence: 55.5%, leaf: 69.6%, stem: 71.6%, root: 67.4%), followed by -caryophyllene (inflorescence: 19.4%, leaf: 14.4%, stem: 12.8%, root: 15.3%). the oils from the whole plant of the samples b, c and d were rich in -pinene (sample b = 23.4%, sample c = 14.4% and sample d = 12.0%), and germacrene d (sample b = 13.2%, sample c = 15.3% and sample d = 16.1%). the obtained data showed the occurrence at least two chemotypes of a. conyzoides in par'a: the type rich in precocene i, comparable to the oils from cameroon, ghana and burkina faso, and southeast of brazil, and the type rich in -pinene/germacrene d.