Saliva is a readily accessible mucosal secretion and salivary antibodies reflect the repertoire of gut-associated antigens; it therefore appears to be ideal for the study of gastro-intestinal disease. A study of salivary immunoglobulins in healthy white and black adults and patients with oesophageal cancer showed that salivary immunoglobulin A levels were higher (but not significantly) in whites than blacks. The levels, however, were similar in healthy blacks and oesophageal cancer patients. There is a wide variation in normal levels of salivary immunoglobulins. Also, immunoglobulins are readily influenced by physiological factors and so at present are unreliable indices of gastro-intestinal disease.