Background/aim: The root gall nematode Meloidogyne incognita constitute the most damaging species that infects many crops in Algeria. The intense use of harmful agricultural chemical products has incited research to develop alternative methods with natural and ecological advantages like essential oils extracted from plants. The objective of this study was to evaluate the efficacy of Origanum vulgare subsp. glandulosum Desf. (Lamiaceae) essential oil on the development of the root-knot nematode M. incognita in potted tomatoes. Materials and methods: In pot trials, we assessed the activity of O. vulgare subsp. glandulosum essential oil at two concentrations of 0.75 and 0.37 mg /L against M . incognita. These dilutions were applied in two treatments to soil: the preventive treatment (pretomato planting), and the curative treatment (posttomato planting), using an artificially inoculated tomato under controlled conditions. Results: The application of O. vulgare subsp. glandulosum essential oil was very effective at the pretomato planting treatment compared to the chemical treatments, and the inoculated control. We noted a reduction in number of roots and soil juveniles, galling index, and an increase in the tomato root and stem weights. The phytochemical screening of O. vulgare subsp. glandulosum revealed the presence of five classes of bioactive compounds (glycosides, saponins, flavonoids, tannins, and gallic tannins). Conclusion: This study showed a potential nematicidal effect of O. vulgare subsp. glandulosum essential oil on root-knot nematode.