As early as in the twenties and thirties of our century Ernst Scharrer published papers suggesting, on the basis of morphological findings, that the brain exhibits secretory function which he called neurosecretion. Only a few decades later Scharrer's presumption was fully confirmed by the isolation of a number of neuropeptides and by the disclosure of their chemical stuctures. Neuropeptide research is one of the most rapidly expanding fields in biomedicin. Initially investigators focused their attention on the existence and role of neuropeptides within the hypothalamo-hypophyseal system. This particular area of research still provides plenty of interesting and fruitful findings. Neuropeptides -including those which were discovered as "hypothalamic" hormones­ can also be detected in other parts of the brain and even in peripheral organs. In fact, several neuropeptides were found to be synthesized not only by neurones but also by non-neuronal cells. These observations imply much wider functional relevance of neuropeptides than it had been supposed initially. It appears from present day knowledge, that neuropeptides are not only involved in neurotransmission and in the control of pituitary function but also in direct regulation of numerous peripheral biological processes, including reproduction, digestion, immune functions, and even cell growth. This volume includes the invited papers of the Symposium on "Progress in Neuropeptide Research" wh ich was held in Looz/Poland on September 8-10,1988. Topics of the symposium reflect upon newly discovered peptides, new localizations, new functions, and new technical approaches.