This article is a review of aspects of the expression of the regulatory peptides; epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and their receptor (EGF-R) in the epithelium of the human oesophagus and stomach in health and disease. It has become clear that TGF-alpha has increased expression in metaplastic, dysplastic and neoplastic tissue of the oesophagus compared with normal mucosa. The degree of abnormal expression becomes more marked as dysplasia increases. TGF-alpha expression is also increased in gastric neoplasias. EGF has a different pattern of expression, being decreased in oesophagitis and increased in gastritis. Although EGF is present in Barrett's oesophagitis, the expression of EGF does not discriminate between dysplastic and neoplastic epithelium. EGF-R is normally expressed on all gastro-intestinal epithelia, but its expression is increased in Barrett's epithelium, as well as in adenocarcinomas of the oesophagus and the stomach. The two peptides bind to their receptors on the mucosal cell membranes, and the co-expression of peptide and receptor is positively associated with varying degrees of cellular proliferation. The density of receptor expression may modulate the proliferative stimulus, leading to either mitogenic (regulated) or oncogenic (unregulated) growth.