TFF-peptides (i.e. TFF1, TFF2, TFF3; formerly P-domain peptides, trefoil factors) have been established as secretory products typical of the gastrointestinal tract. Their synthesis has recently been recognized in a number of mucin-producing epithelial cells, for example, of the respiratory tract, the salivary glands, the uterus and of the conjunctiva. They have a pivotal role in maintaining the surface integrity of these delicate epithelia as constituents of mucus gels as well as by their anti-apoptotic properties and their motogenic activity modulating cell migratory processes. The latter is important for rapid healing in particular of gastrointestinal and respiratory epithelia by a process termed "restitution". On the other hand, one of these peptides--namely TFF3--has been detected as a new neuropeptide of the human hypothalamo-pituitary axis where it is synthesized in oxytocinergic neurons of the paraventricular and supraoptic nuclei. From there it is transported to the posterior pituitary where it is released into the blood stream. Synthesis of TFF-peptides also occurs pathologically as result to chronic inflammatory diseases, for example of the gastrointestinal tract. Aberrant synthesis of TFF-peptides is observed in many tumors.