The essential oils of Actinolema macrolema Boiss. (Apiaceae) were obtained by hydrodistillation in the first 3 (sample A) and the following 3 h (sample B) from crushed fruits and dried leaves (sample C), which were subsequently analyzed by GC and GC-MS. Overall, 64 components were characterized, representing 93% of the leaf oil. Thirty components were characterized from the fruit oil representing 95% of the first fraction and 90% of the second fraction consecutively. Guaia-5,7(11)-diene, selina-3,7(11)-diene, and juniper camphor were isolated from the oils by column chromatography and their structures were elucidated by GC-MS, H-1 NMR, and C-13 NMR. The occurrence of guaia-5,7(11)-diene in nature is reported for the first time. Guaia-5,7(11)-diene (37% and 30%), germacrene-B (25% and 21%), and selina-3,7(11)-diene (both 12%) were found as major components in the oil of sample A and the following sample B, respectively. In sample C, 1-octadecanol (24%) and hexadecanoic acid (19%) were identified as the major components. Additionally, antimicrobial activities of the fruit oils were determined using broth microdilution. Sample A exhibited relatively good inhibition of Staphylococcus epidermidis (MIC 62.5 mu g/mL). The 2 fruit essential oils showed inhibitory (MIC 125 mu g/mL) effects equal to those of the standard antifungal agent used against C. albicans.