Abstract: In the first part of the study, the concentration of enrofloxacin and its main metabolite in chicken feces were examined at the dosage of 2.5, 5 and 7.5 mg/kg body weight respectively by high-performance liquid chromatography (HPLC) with fluorescence detection. In the second part of the study, the degradability of enrofloxacin in chicken feces was tested under different form of illumination. The results were as follows: After administration in healthy chicken, enrofloxacin was excreted in feces as the parent compound (main form) and its metabolite as ciprofloxacin. When the oral dosage was 2.5 mg/kg and 5.0 mg/kg body weight, the concentration of enrofloxacin and ciprofloxacin in chicken feces reached the peak at the 6th hour and at the 4th hour after administration respectively. When the oral dosage was 7.5 mg/kg body weight, the concentration of enrofloxacin and ciprofloxacin reached the peak at the 9th hour and at the 6th hour after administration respectively. At 10th day after administration, enrofloxacin and ciprofloxacin couldn’t be detected in chicken feces. The degradation of enrofloxacin in chicken feces was affected by illumination. Enrofloxacin in chicken feces was very stable in photophobic condition. But under daylight illumination, the degradation rate of enrofloxacin was very fast in chicken feces. The degradation process of enrofloxacin in chicken feces could be evaluated on the basis of the first order kinetic equation as C_t=C₀e^-kt. Calculated by this equation, the half-life of enrofloxacin in chicken feces was(2.23±0.25)d under daylight illumination.