A novel and simple method of luminescence enhancement effect for the determination of trace amounts of bile acid was proposed. The procedure was based on the luminescence intensity of the balofloxacin-europium(III) complex that could be strongly enhanced by bile acid in the presence of sodium dodecyl benzene sulfonate (SDBS). Under the optimum conditions, the enhanced luminescence intensity of the system exhibited a good linear relationship with the bile acid concentration in the range $5.0{ imes}10^{-9}-7.0{ imes}10^{-7};mol;L^{-1}$ with a detection limit of $1.3{ imes}10^{-9};mol;L^{-1}$ ($3{sigma}$). The relative standard deviation (RSD) was 1.7% (n = 11) for $5.0{ imes}10^{-8};mol;L^{-1}$ bile acid. The applicability of the method to the determination of bile acid was demonstrated by investigating the effect of potential interferences and by analyzing human serum and urine samples. The possible enhancement mechanism of luminescence intensity in balofloxacin-europium(III)-bile acid-SDBS system was also discussed briefly.