Root-knot nematodes (RKN;Meloidogynespp.) are obligatory endoparasites with worldwide distribution which cause severe damage to agricultural crops. The present study aimed to define the nematicidal activity of thymol on different life stages of the root-knot nematodeMeloidogyne javanica(Treub) Chitwood, at concentrations of 37.5–1000 μL/L. This study is the first to report the effect of thymol on egg differentiation and also its vapor and sublethal concentration activities. A mortality of greater than 90% ofM. javanicasecond-stage juveniles (J2s) occurred after 96 h of exposure at a concentration of 500 μL/L. At this concentration, thymol inhibited 59.7% of nematode hatching. In addition, the use of thymol at sublethal concentrations reduced the number of females per gram in tomato roots in a pot test, as well as inhibiting egg differentiation. On the contrary, no nematostatic effects were observed in paralysis bioassays. The results presented here indicate that the use of thymol may show its potential as a source of a new sustainable nematicidal product.