The indication for morphine use is primarily pain, but also a combined analgesic and sedative effect may be the rationale behind morphine administration. Paediatric morphine regimens have been reported for children with postoperative pain, pain related to cancer, sickle cell crisis pain, burns and AIDS. No dose response curve for morphine in neonates, infants or children has been established, and different levels for the minimum effective plasma concentration have been estimated. The side effects observed in neonates, infants, and children are similar to those observed in adults, and neonates do not seem to be more susceptible to respiratory depression than older children. Despite shortcomings in the knowledge of the pharmacodynamics of morphine, it can be considered safe to administer morphine to neonates, infants or children. Initial regimens has been calculated from the pharmacokinetic parameters of morphine, but treatment must be adjusted according to analgesic effect and incidence of side effects.