A method is described for dispersal and subsequent maintenance in acute culture of neurones dissociated from ganglia of the adult cockroach (Periplaneta americana) and brain of the adult fly (Musca domestica). The effects of different media on the survival and attachment to different substrates have been investigated. About 25% of dissociated neurones survived well for periods greater than 6 days in a cockroach saline supplemented with foetal calf serum and the antibiotics fungizone and gentamicin. Fly neurones were more difficult to disperse. Fly saline supplemented with foetal calf serum and the antibiotics fungizone and gentamicin proved a successful short-term culture medium. Survival times were shorter, most neurones dying after 5 days. The demonstrated viability of such neurones has considerable potential for insecticide mode of action studies using the patch-clamp technique.