A liquid chromatography procedure for routine determination of urinary estriol concentrations is described. After enzymic hydrolysis of a 1 ml sample, automatic extraction with chloroform/ethyl acetate, purification by chromatography on a disposable "minicolumn" of AG 1-X2, urinary estrogens are separated with normal phase column and isocratic elution with isooctane/ethyl acetate/methanol/water and the optical density at 280 nm is measured. The specificity is assessed by comparison of liquid chromatography with fluorometry and gas liquid chromatography. The technique is simple, rapid and quite suitable for routine determination.