Abstract The structure of the secretory tissues and the essential oil of the leaves of Croton campestris St Hil. were studied. The oil isolated by hydrodistillation was analyzed by GC and GC/MS and was found to contain 75 components accounting for 92.9% of the total oil, with the major components being caryophyllene oxide (29.9%) and humulene oxide II (8.0%). Growth inhibitory activity of the active compounds in solution was evaluated by measuring Minimal Inhibitory Concentration using a broth micro-method. The Minimal Inhibitory Concentration of the leaf oil was 1.56 µg/mL for Staphylococcus aureus, 6.25 µg/mL for Enterrococcus hirae and 6.25 µg/mL for Candida albicans.