Whole cell currents induced by the excretions of venom glands from the spider Araneus diadematus (ASV) were tested in neurones from the embryonic spinal cord of the chick in culture by the patch clamp technique. ASV in a dose of one bite in 1 ml induced a large membrane current of the same polarity as the excitatory amino acids, which decreased during long-lasting application. The effects were, to a large extent, rapidly reversible. It is suggested that ASV activates and desensitizes the receptor channels for excitatory amino acids.