Laminin is a component of the extracellular matrix and is associated with tumor cell metastasis. Present studies show that the ovarian cancer cell lines produce significant amounts of laminin (54-140 ng/ml) in culture. Since ovarian cancer is associated with ascites production, laminin levels were then determined in ascites and serum. The results indicate that the ascites from patients with serous adenocarcinoma of the ovary had higher levels of laminin than the normal peritoneal fluid (P < 0.0001). However, the serum levels of laminin did not differ significantly between the control population and ovarian cancer patients.