The essential oil from the rhizomes of Aframomum sceptrum (Zingiberaceae) was analyzed by GC/MS, and its major constituents were found to be beta-pinene (12.7%), caryophyllene oxide (10.0%), and cyperene (6.0%). The oil was also evaluated for antimicrobial activities, in comparison with beta-pinene, caryophyllene oxide, and the leaf essential oil of Melaleuca alternifolia (Myrtaceae). The A. sceptrum essential oil exhibited bacteriostatic activity against the Gram-positive bacteria Bacillus subtilis, Staphylococcus epidermidis, and S. aureus, but not against Gram-negative bacteria. Moreover, it showed mild fungicidal activity against Candida albicans and Aspergillus fumigates, and remarkable antiprotozoal activity against Trypanosoma brucei brucei (MLC of 1.51 mu l/ml) and Trichomonas vaginalis (IC(50) of 0.12 +/- 0.02 and MLC of 1.72 mu l/ml).