the foliage essential oils (obtained by hydro-distillation) of male and female plants of juniperus communis l. subsp. hemisphaerica, collected from wild habitat were estimated in three different seasons (spring, summer and autumn). the highest essential oil content was obtained from male plants in spring (3.40%). gc and gc/ms analysis of foliage oils showed that the monoterpenes (77.1-88.7%) were the major groups of compounds, followed by amount of sesquiterpenes (4.3-6.3%). the major constituent of the both male and female foliage oils in spring and autumn was -pinene. in the samples collected during summer, essential oil was dominated by -pinene (48.8%) and sabinene (44.5%) for male and female plants, respectively. the concentration of -pinene in the foliage oils from the male plants was higher than in the oils from the female plants. in the present experiment, the variations chemical composition of essential oil were mainly due to the differences in type of the foliage (extracted from male or female plant) and harvest season. in conclusion, foliage of j. communis l. subsp. hemisphaerica for obtaining higher essential oil content (3.40%), -pinene (61.69%) and limonene (13.56%) should be collected from male plant during the spring season (or at the flowering stage).