Structural properties (using gas chromatographic analyses: gas chromatography and gas chromatographymass spectrometry) of some compounds (pure chemicals, essential oils, extracts, etc.) and systematic investigation of antimicrobial activities (with agar dilution and agar diffusion disc methods) were determined in the fruits of Kefe cumin (Laser trilobum L.) obtained from different regions (Germany, India, and Turkey). The main components were established as limonene (41.0372.24%) and perillaldehyde (4.2332.75%) in the essential oils determined by gas chromatographymass spectrometry. Mineral contents in the fruits were determined by inductively coupled plasma atomic emission spectrometer. It was determined that the fruits were rich in potassium, calcium, phosphorus, magnesium, sodium, arsenic and aluminium minerals. The highest sodium content was found to be 9,261.28mg/kg in the samples obtained from Turkey, but the potassium content of the samples from Germany and India was higher than that of Kefe cumin fruits obtained from Turkey. The fruit extracts had a significant antimicrobial effect on pathogen bacteria such as Staphylococcus aureus, Proteus vulgaris (FMC 1), Proteus mirabilis, Bacillus cereus (FMC 19), Aeromonas hydrophila (ATCC 7965), Enterococcus faecalis (ATCC 15753), Klebsiella pneumoniae (FMC 5), Salmonella typhimurium, Enterobacter aerogenes (CCM 2531) and Escherichia coli (ATCC 8739), whereas no significant antimicrobial effect of the essential oils was observed. © 2009 Informa UK Ltd.