abstract the essential oil isolated by hydrodistillation from unripe fruits of myrcia laruotteana camb. (myrtaceae) was analyzed by gc and cg/ms. forty-four components were identified, representing around 83% of total oil. the major components were -bisabolol (23.6%) and -bisabolol oxide b (11.5%). the cytotoxicity of the oil and of a fraction rich in -bisabolol was tested in vitro against u251 (glioma), uacc-62 (melanoma), mcf-7 (breast), nc1-adr/res (ovarian-resistant), 786.0 (kidney), nci-h460 (lung), pc-3 (prostate), ovcar-3 (ovarian), ht-29 (colon) and k562 (leukemia) human cancer cells and against vero (no cancer cell). the oil exhibited antiproliferative activity against all cell lines (tgi < 100 g/ml), with exception of nci-h460 cell line (tgi > 125 g/ml). the highest activity of the oil was observed against u251 (tgi 20.46 g/ml), 786.0 (tgi 20.74 g/ml), uacc-62 (tgi 26.98 g/ml) and pc-3 (tgi 27.63 g/ml) cell lines. the fraction rich in -bisabol showed a similar activity profile. it was most active against ovcar-3 (tgi 8.58 g/ml) and 786.0 (tgi 8.74 g/ml).