A semi-automatic extractor was developed which processes 12 urines at a time to a stage where 'total' oestrogens can be measured by colorimetry using the Kober reaction (late pregnancy urines) or by fluorimetry using the Kober\p=m-\Ittrich procedure (non-pregnancy and early pregnancy urines). One worker can complete 12 analyses in 3\ m=1/ 2\ hr. or 24\p=n-\36 in a working day. The results obtained at oestrogen levels above 1 mg./24-hr. urine were the same as those obtained by a method specific for oestriol. The results obtained from non-pregnancy urines were compared with the sums of oestriol, oestrone and oestradiol obtained by the method of Brown (1955). The mean ratio (\ m=+-\ s.d.) of the two values was 1\m=.\22 \ m=+-\ 0\m=.\31. The comparisons indicated that the short procedure was the more reliable method at levels below 5 \ g=m\ g. / 24-hr. urine. Values for normal subjects are given. The methods appear to be entirely suitable for assessing oestrogen production by the ovaries, testes, adrenals and placenta.

Higher temperatures allow lower sulphuric acid concentrations and shorter heating times to be used in the Kober colour reaction for oestrogens. A one-stage reaction which is completed in 5 min. at 120\s=deg\is described for oestrone and oestradiol, and a two-stage reaction which requires two periods of heating for 5 min. at 120\s=deg\is described for oestriol. The conditions were applied to the Ittrich fluorescence procedure. A spectrophotofluorimetric correction was developed in which fluorescence was measured at wavelengths for excitation and emitted light near the optima for the oestrogens and at another combination at which the oestrogens produced virtually no fluorescence whereas that of impurities was not diminished. Extraction, centrifugation and fluorimetry were performed in specially designed cells. The sensitivity is 0\ m=. \ 05\ p=n-\ 0\ m=. \ 1 ng./sample with a linear response up to 300 ng. and a precision better than 4% in the range 1\m=.\0\p=n-\100 ng.