The review focuses on the progress in recent decades on various aspects of molecular responses taking place in plants infested by herbivorous arthropods. The diversity of herbivoryinitiated molecular events was presented with special emphasis on: (1) elicitors and a general recognition process, (2) signal perception, transduction, integration and defence gene expression, (3) cross-talk between salicylate- and jasmonate-dependent defence pathways, and (4) regulators of plant defence responses.