〔Abstract〕 Objective To study the guidance effects of fibroblast growth factor 3(FGF3) on the prethalamic γ-aminobutyric acid(GABA) inhibitory axons, and to explore the effect of FGF3 on the formation of thalamic axonal network. Methods Expression and localization of FGF3 and prethalamic GABA marker gene in chicken embryonic diencephalon were detected by immunofluorescence. Early orientation of GABA axons was tracked by DiI. Three-dimensional gel co-culture experiment was carried out to investigate guidance effects of FGF3 on early prethalamic GABA inhibitory axons.Results Prethalamic GABA cells were adjacent to the FGF3 + hypothalamas, located a-bove the hypothalamus. DiI tracing experiments revealed that prethalamic GABA inhibitory axons had already ex-tended into the thalamus at E6. Compared with the blank control group, FGF3 not only significantly promoted thegrowth of prethalamic GABA inhibitory nerve fibers in the prethalamus, but also repelled the newborn prethalamicaxons to the dorsal thalamus. The number of prethalamic axons was significantly less in proximal section(towardsFGF3 beads) than that in distal section(away from FGF3 beads)(P<0. 01). Moreover, the guidance effects ofFGF3 on prethalamic axons could be blocked by the FGF pathway inhibitor SU5402.Conclusion FGF3, an axonguidance molecule expressed in hypothalamus, exerts guidance effects on the pathway selection of adjacent prethal-amic GABA inhibitory nerve fibers.