The volatile constituents from flower, leaf and stem of Gypsophila bicolor growing in Iran were obtained by hydrodistillation and analyzed by GC and GC/MS. The flower oil was characterized by high amounts of germacrene-D (21.2%), p-cymene (20.6%), bicyclogermacrene (17.6%), gamma-dodecadienolactone (13.7%) and terpinolene (9.4%). Twenty-four constituents representing 97.4% of the leaf oil were identified of which germacrene-D (23.4%), terpinolene (14.5%), bicyclogermacrene (7.5%), gamma-dodecadienolactone (6.8%), p-cymene (6.7%) and cis-beta-ocimene (6.3%) were major components. The main components of the stem oil were gamma-dodecadienolactone (28.5%), bicyclogermacrene (14.8%), germacrene-D (12.6%), p-cymene (12.5%), terpinolene (11.6%) and trans-beta-ocimene (4.2%). The antimicrobial effects of flower, leaf and stem essential oils from Gypsophila bicolor were studied according to the agar diffusion cup method. The essential oils had a moderate effect on the Gram-positive and Gram-negative bacteria, but had a substantial effect on the fungi studied.