Four biochemical parameters, soluble oestradiol (REC) progesterone (RP) receptors, 17B oestradiol and isocitric dehydrogenase enzymes were studied to evaluate hormone sensitivity in 51 patients with endometrial carcinoma. Samples of tumours were taken before and after 7 to 14 days of oral medroxyprogesterone acetate (MPA) treatment for histological and biochemical analysis. Hormone sensitivity assessed by a decrease in receptor concentration after MPA in REC rich (p less than 0.005) and RP rich (p less than 0.02) tumours was 65% and 63% respectively. Induction of isocitric dehydrogenase enzyme with MPA was highly significant in REC rich (p less than 0.0001) and RP rich (p less than 0.001) tumours, as was the induction of 17B oestradiol dehydrogenase in REC rich (p less than 0.01) and RP rich (p less than 0.005), confirming progestogen sensitivity. Post MPA dehydrogenase enzyme levels predicted survival more accurately than pre MPA receptor status of the tumours.