Compositional characteristics of the essential oils of four Ocimum spp., namely Ocimum adscendens Willd., Ocimum gratissimum L., Ocimum tenuiflorum L. and Ocimum americanum L. were examined using GC-FID, GC-MS, and hierarchical cluster analyses from peninsular India. The essential oil content varied from 1.0% to 2.0% in different Ocimum spp. Altogether eighty-four constituents, corresponding to 89.9â96.5% of the total oil compositions were identified. Major constituents of O. adscendens oil were eugenol (47.6%), (E)-caryophyllene (15.7%) and β-elemene (11.3%). O. gratissimum oil was characterized by the presence of higher amounts of eugenol (52.9%), caryophyllene oxide (7.2%) and (Z)-β-ocimene (3.5%). Major constituents of O. tenuiflorum oil were methyl eugenol (50.9%), caryophyllene oxide (7.5%) and (E)-caryophyllene (5.5%). Moreover, the oil of O. americanum was dominated by camphor (41.8%), limonene (7.1%), α-pinene (6.2%), β-selinene (5.6%) and camphene (5.0%). To the best of our knowledge, a detailed essential oil profile of O. adscendens is being reported for the first time.