The pathogenesis of the neurotoxicity of most antineoplastic drugs is unknown. Recent reports suggest that changes in the circulating levels of nerve growth factor (NGF) might be related to the dorsal root ganglia sensory neuron damage induced by cisplatin (CDDP), the first member of a family of widely used and very effective platinum-derived anticancer agents. Using a well-characterized model of CDDP neurotoxicity, we demonstrated that the NGF circulating level decreased during chronic CDDP administration in close accordance with the clinical course and returned to normal levels after recovery from the neurotoxic damage. Moreover, these changes were restricted to NGF and did not involve other trophic factors of the same neurotrophin family. Our findings are in agreement with previous in vitro and in vivo results and further suggest that NGF plays a specific role in the course of CDDP-induced primary sensory neuron damage.