Abstract: A glycoprotein having a molecular weight of 28,000 to 32,000 and an isoelectric point of 7.0 to 9.0, both as determined by two-dimensional SDS polyacrylamide gel electrophoresis, is synthesized and secreted specifically by stromal cells of endometriotic origin. Amino acid residues in the region of the N-terminus of the glycoprotein share amino acid sequence identity with a region of tissue inhibitor of metalloproteinases-1 (TIMP-1). A method of screening for endometriosis is disclosed by detection of lower levels of the protein or TIMP-1 in peritoneal fluid or serum samples of women.