We describe six pregnancies in five patients with Cushing's disease --four had undergone transsphenoidal surgery, with improvement but no cure of their hypercortisolism; the other woman became pregnant during initial work up. At conception, none of the patients were receiving specific treatment for hypercortisolism. Mean free urinary cortisol (FUC) prior to pregnancy was 430 nmol/24 h (normal range: 51-280). In two patients, FUC throughout pregnancy increased significantly, but no clinical progression was observed. FUC measured in 20 healthy pregnant women was found to rise above the normal non-pregnant range ( < 280 nmol/24 h) in the second (mean +/- 2 S.D. = 463 +/- 256 nmol/24 h; P < 0.01) and third trimester (424 +/- 210 nmol/24 h; P < 0.05). However, in the Cushing patients values were higher. Two pregnancies ended in spontaneous abortions, one resulted in an ectopic pregnancy, and the remaining three were followed to term of which one developed third trimester gestational diabetes, and her baby developed neonatal sepsis which resolved uneventfully. We conclude that despite high abortion and ectopic pregnancy rates, a remarkably uneventful and uncomplicated outcome with no clinical progression of cushingoid symptoms, was observed in two of the three pregnancies followed to term, despite significant increases in FUC.