Colchicine was used to inhibit axonal transport and to demonstrate that rabies virus spread from the peripheral inoculation site to the CNS by the retrograde axoplasmic flow. Colchicine was applied by the mean of elastomer implants around the sciatic nerve of young rats in order to obtain higher local concentrations of the drug. This procedure avoided the systemic effects of colchicine encountered with the usual treatment. To confirm the efficiency of the axoplasmic flow inhibition by colchicine, 125I-tetanus toxin was used as a marker. Uptake of colchicine by the sciatic nerve was monitored by the use of 3H-labelled colchicine. Interruption of the retrograde axoplasmic flow resulted in prevention of fixed and street rabies virus propagation. Moreover, the centrifugal spread of rabies of rabies could be inhibited using this experimental procedure.