Phytohormones mediate important aspects of developmental processes in plants and may participate in various aspects of plant nematode interactions. Several reports demonstrate that nematode infection interferes with plant auxin flow and accumulation, and that auxin is necessary for feeding site formation. Other plant hormones, such as ethylene, might be modulating several cellular processes during feeding site formation. So far, the nematode molecules involved in activating these processes in planta have not been identified. Auxin can act as a signalling molecule by inducing changes in the surface cuticle and behaviour of Meloidogyne spp. and these changes might be essential for infection. Auxin binds to the chemosensory organs, amphids and phasmids and also to several tail neurons of Meloidogyne spp. This interaction might allow these nematodes to sense and follow an auxin gradient through amphidial or phasmidial receptors during penetration and migration inside roots.