Nuclear and cytoplasmic oestrogen receptors (REN and REC) were sought in 5 normal cervices and in 43 specimens of squamous carcinoma of the cervix. All 3 tissues components of the 5 normal cervices contained both REN and REC. Thirty-five (81%) of the tumours contained receptors, but in only 9 (21%) were they found in both subcellular compartments. Twenty-four tumours (56%) had only REC and 2 had only REN. The potential therapeutic significance of these findings is not yet known, but it seems possible that tumours with an intact receptor mechanism might benefit from oestrogen therapy and have a more favourable prognosis.