Abstract : The present work involves research into the herbicidal activity of Eucalyptus globulus essential oil collected from souk ahras (north-east algeria), on the germination and growth of Sinapis arvensis and Triticum turgidum seeds. The oil was isolated by hydrodistillation in a Clevenger-type apparatus and analyzed by GC/MS. The yield of the essential oil was 2.6% and 38 constituents were identified. The major constituents of the oil were Spathulenol (22.68%), p-Cymene (21.82%), Beta –Phellandrene (15.73%) and Cryptone (4.73%). The EO was subjected to anti-germination and phytotoxic tests. The results of the treatments showed that the oil exerted a considerable inhibitory effect on the germination and growth repression of field mustard seeds, although it appeared to have no effect on the germination of durum wheat seeds.