Samples of 21 ovarian cancers were assayed for oestrogen receptor (ER) and progesterone receptor (PR) content, and the response in vitro to treatment with a combination of doxorubicin, diacetyldian hydrogalactitol and cisplatin was determined. The number of living cells after drug exposure was estimated by a new ATP-bioluminescence method and the tumours were considered responsive if cell survival was less than or equal to 50% of the value in a corresponding control culture. Of the 16 tumours that responded to drug exposure, nine were ER-positive, seven ER-negative and eight were PR-positive, eight PR-negative. The mean percentages of surviving cells ranged from 22.2% in PR-negative tumours to 30.9% in PR-positive tumours. There were no differences in the response rates or in the degree of response to the cytostatics in terms of either receptor status or tumour histology. The results were also compared with those obtained in the same tumour samples exposed to hormones, tamoxifen and medroxyprogesterone acetate. The average response of all tumours was better to cytostatics than to hormones (P less than 0.05); this was particularly marked in the ER-negative tumours. Cytostatics may be preferable to hormones as the primary drug treatment for ovarian cancers but steroid-receptor determinations appear not to help in formulating the optimum drug treatment.