As a kind of environmental endocrine disruptors, bisphenol A received a wide attention around the world. The planar waveguide fluorescent biosensor can rapidly and sensitively detect traceable bisphenol A in water samples. Under the optimized test conditions, the typical calibration curve for BPA determination by the biosensor showed a detection limit of (0.04 +/- 0.007) microg x L(-1) The linear response ranged from 0.16 microg x L(-1) to 22.40 microg x L(-1). The 50% inhibition concentration (IC50) was (1.67 +/- 0.47) microg x L(-1). By means of adding 0.5% EDTA to sample solutions could weaken the interference of water hardness. Under the optimal conditions, the recovery ratios for four kinds of real water samples were in the range of 88% to 111%, with R.S.D. less than 15%. The results indicate that this method features the potential in the practical detections of bisphenol A in real water samples.