With the current incremental trends in the prescription of second-generation antipsychotics (SGA) due to their fewer neurologic side effects compared to first-generation antipsychotics, the metabolic side effects of these drugs are coming into view. Weight gain is the most common and arguably one of the most troublesome side effects of atypical antipsychotics. Other SGA-induced side effects include impairment of lipid and glucose metabolism. SGA-induced weight gain is usually the product of disturbances of complex series of genetic and biochemical processes that are not completely understood to this day. Myriads of studies have provided convincing evidence for metabolic adverse effects of second-generation antipsychotics in adults, but their effect on paediatric populations is still not clear as studies on children and adolescents have been less extensive. The aim of this thesis is to review published literature data based on available basic and clinical studies to evaluate the comparative effects of atypical antipsychotics on the weight of children and adolescents, particularly those treated in inpatient settings.