The distribution between the aqueous and solid phase of 17 beta-estradiol in the ng-range in waste water was investigated by spiking experiments with a radio-labeled hormone. The distribution was measured by liquid scintillation counting. The major part of 17 beta-estradiol remained in the aqueous phase and did not adsorb to the solids. The fraction in the aqueous phase could be enriched by a conventional solid phase extraction with a recovery rate of up to 100%. Losses were negligible and the compound did not adsorb to the surfaces of glass bottles.