Delirium is a serious neuropsychiatric disorder and pediatric delirium (PD) is a similarly serious condition. PD is understudied and very often misdiagnosed, especially in pediatric intensive care units (PICU). It is important to early diagnose PD, so that early psychosocial interventions and therapy can be introduced. Valid diagnostic instruments are needed at PICU to assess PD. There are many scales and tests to diagnose delirium but none of them is specific enough to diagnose PD. Although PD is a serious complication at PICU, clinical guidelines for PD are still lacking, therefore additional investigations are needed to bring them out.