Part 1 Molecular biology: invited lectures - melatonin receptors and signal transduction mechanisms, P. Barrett et al, structure-affinity relationships of indole-based melatonin analogs, G. Spadoni et al, indole melatonin agonists and antagonists derived by shifting the melatonin side chain from the C-3 to the N-1 or to the C-2 indole position, G. Tarzia et al, methods for the evaluation of drug action at the human melatonin receptor subtypes, R. Nonno et al, melatonin as a time-meaningful signal in circadian organization of immune response, D.P. Cardinali et al, new actions of melatonin on tumour metabolism and growth, D.E. Blask et al, the oxidant/antioxidant network - role of melatonin, R.J. Reiter et al; selected communications - effects of near-ultraviolet (UV-A) light on melatonin biosynthesis in vertebrate pineal gland, J.B. Zawilska et al, cyclic 3-hydroxymelatonin - a melatonin biosynthesis generated as a result of hydroxyl radical scavenging, D.-X. Tan et al, antiproliferative effects of melatonin and CGP 52608, M. Karasek and M. Pawlikowski. Part 2 Clinical applications: invited lectures - the dim light melatonin onset, melatonin assays and biological rhythm research in humans, A.J. Lewy, the use of melatonin for the treatment of insomnia, N. Zisapel, melatonin in circadian sleep disorders in the blind, D.J. Skene et al, a melatonin preparation with a pulsatile liberation pattern - a new form of melatonin in replacement therapy, A. Hoffman et al, melatonin in epilepsy -first results of replacement therapy and first clinical results, J.-D. Fauteck et al, melatonin influences human balance, F. Fraschini et al, melatonin in psychiatric disorders - subtyping affective disorder, B. Wahlund; selected communications - effect of melatonin in selected populations of sleep-disturbed patients, L.I. Brusco et al, suppression of UV-induced erythema by optical treatment with melatonin - influence of the application time point, T. Fischer et al, protective effect of melatonin on zymosan-induced cellular damage, S. Cuzzocrea and A.P. Caputi, aspects of melatonin manufacturing and requirements for a reliable active component, R. Laforce et al.