Abstract: In a Briton-Robinson(BR) buffer solution of pH 4.1~5.0, some fluoroquinolone derivatives(norfloxacin, NRF; ciprofloxacin, CPF; ofloxacin, OFL; levofloxacin, LVF) were reacted with palladium(Ⅱ) to form anion chelates, but their resonance Rayleigh scattering(RRS) was very weak. Significant enhancement of RRS intensity and new RRS spectra were observed when these anion chelates further reacted with eosin Y to form ternary complexes. These ternary complexes had similar spectral characteristics and their maximum RRS peaks were located at 368 nm. The optimum condition and the affecting factors were investigated. The linearity ranges and the detection limits for the four fluoroquinolone derivatives were 0~2.4×10^-6 g/mL and 9.4×10^-9 g/mL(CPF), 0~2.4×10^-6 g/mL and 12.8×10^-9 g/mL(NRF), 0~2.2×10^-6 g/mL and 16.2×10^-9 g/mL(LVF), 0~2.8×10^-6 g/mL and 15.6×10^-9 g/mL(OFL), respectively. The composition of the ternary ion association complex was 1:1:1 and its reaction mechanism is discussed. The method has been successfully applied to the determination of NRF in injection and in chicken serum samples and its recovery ranges from 95.0% to 101.5%. As a result, a sensitive and selective RRS method has been developed for the determination of some fluoroquinolones antibiotics.