On 1st May 2017, journal club meeting, the topic “The therapeutic actions of melatonin: A brief look at its possible protective role in AlP poisoning.” was discussed. Melatonin is a phylogenetically well-preserved molecule with diverse physiological functions. In addition to its well-known regulatory control of the sleep/wake cycle, as well as circadian rhythms generally, melatonin is involved in immunomodulation, hematopoiesis, and antioxidative processes. Recent human and animal studies have now shown that melatonin also has important oncostatic properties. Both at physiological and pharmacological doses, melatonin exerts growth inhibitory effects on some cancer cells.