A simple homogeneous fluorescence polarization receptor assay (FPRA) was developed to measure the receptor binding activities of various endocrine disrupters using ethylenediamine fluoresceinthiocarbamyl (EDF)-labeled estrogen and estrogen receptor. Cytosolic receptor was isolated from rat uterine and EDF-estrogen tracers were synthesized by EDC coupling reaction. After selection of a best matching pair of uterine cytosolic receptor and EDF-estrogen tracer, calibration curve of FPRA was established using 17β-estradiol (Kd = 4.6 x 10-8 M) which can bind with estrogen receptor in the range between 100 nM and 1 mM. Using this system, the receptor binding activities of various endocrine disrupting chemicals were investigated and relative estrogen binding activities were characterized. This FPRA system, which needs no separation step between free tracer and receptor-bound tracer, takes 20 minutes for 10 samples using photocheck mode of fluorescence polarization analyser.