Analysis of ascites is commonly used to establish clinical diagnoses. On the basis of the protein concentrations and/or specific gravity most ascitic fluids can be classified as either transudates (associated with non-malignant conditions) or exudates (associated with malignant neoplasms or inflammations). However, these determinations frequently are unreliable and problems of distinguishing among such lesions as cancer, tuberculosis, acute infection or pancreatitis often remain. We believe that malignant ascites may have qualitatively and/or quantitatively distinguishable levels of carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP) and/or other tumor markers because of direct release by neoplastic cells present in ascites. We plan to assay CEA (radioimmunoassay) and AFP (modified rocket technique) in ascites and plasma. Serum proteins such as albumin and alpha 1, alpha 2, and beta- globulin will be tested for in ascites to see if the concentration of the tumor markers relative to these proteins will increase diagnostic accuracy. CEA and AFP-like substances will be chromatographically separated and immunochemically characterized and compared to purified CEA and AFP by (a) absorption, (b) immunodiffusion, (c) immunoelectrophoresis, and (d) competitive binding studies. Subsequently new tumor markers will be sought in malignant ascitic fluids. More specific assays will then be developed to aid the diagnosis, prognosis and monitoring of therapy of colonic (and other) cancers.