Decreased expression of NT-3 mRNA in the sciatic nerve and leg muscles of streptozotocin (STZ)-diabetic rats has been associated with the pathogenesis of diabetic neuropathy. The aim of this study was to determine whether STZ-induced diabetes also affects the expression of NT-3 mRNA in the central and peripheral projections of sensory nerves. Competitive reverse transcription-polymerase chain reaction (cRT-PCR) was used to quantify the levels of NT-3 mRNA in the dorsal root, sural nerve, sciatic nerve and foot skin of age-matched and 12-week STZ-diabetic rats. Diabetes increased by 52% (P < 0.05) the expression of NT-3 mRNA in the dorsal root and sural nerve. It is proposed that diabetes-induced sensory nerve damage may elevate NT-3 mRNA production which may act as a source of neurotrophic support for sensory axons whose target-derived supply of NT-3 may be impaired.