The potential of the soluble forms of the adhesion molecules ICAM-1 (sICAM-1), CD44std (sCD44std) and E-cadherin (sE-cadherin) was tested for the diagnosis of benign and malignant cystic epithelial tumours of the ovary. Concentrations of sICAM-1, sCD44 std and sE-cadherin were measured by enzyme-linked immunosorbent assay (ELISA) in the serum and cyst fluid obtained from 23 patients with luteal cysts, 29 with cystadenomas, nine with dermoid cysts, five with borderline tumours and 11 with carcinomas. Serum concentrations of sICAM-1, but not of sCD44std and sE-cadherin, were constantly elevated compared with normal controls. Cyst fluid concentrations of sICAM-1, sCD44std and sE-cadherin were elevated in borderline and malignant tumours compared with cystadenomas (P = 0.034, 0.006 and 0.001, respectively). In conclusion, our results suggest that serum concentrations of adhesion molecules have no diagnostic value in ovarian tumours, whereas cyst fluid concentrations may facilitate distinction between benign lesions and borderline or malignant tumours.