In children with all types of severe neutropenia the development of G-CSF for therapeutic use changed the quality of their life dramatically. Missing the most important cells in the defense against bacterial infections the neutrophilic granulocytes, these patients suffered from episodes of severe, often life-threatening bacterial infections. They spent numerous days in hospital, requiring intravenous antibiotic treatment. Recurrence of bacterial infections at the same site led to irreversible tissue damage, for example in the lung, requiring often disabling surgical interventions. In most patients G-CSF treatment induced an increase of blood and tissue neutrophils to a level high enough to guarantee a normal defense against bacterial infections. The quality of life improved substantially in these children. The fact that they have to inject themselves daily does not cause any problems. Overall, taken in consideration all possible adverse events during our short observation period, all patients who responded to G-CSF benefit from this treatment to a degree never considered to be possible before.