Background: Infections, major surgeries, and hyperinflammatory syndromes are known to trigger Systemic Inflammatory Response Syndrome (SIRS). Discrimination between infectious and noninfectious inflammation often poses a challenge in chronically ill patients with multiple comorbidities. These patients are routinely treated with a variety of anti-infective medications before a pathogen is identified. With the goal of improving pathogen detection rates and interventions, we evaluated Next Generation Sequencing (NGS) as a highly sensitive and fast means of detecting free microbial DNA in a small amount of serum samples from children with ongoing SIRS. Methods: We describe seven complex pediatric patients of SIRS or prolonged fever (>38.5 °C) >72 hours in which serum samples analyzed by NGS had a major impact on therapy. One patient was analyzed twice. Results: In eight NGS there were six positive results (two bacterial, three viral, one fungal) which were subsequently confirmed by microbiological culture or polymerase chain reaction (PCR) in five of the six NGS. In five of the eight performed NGS, results led to a change of therapy: antibiotic therapy was discontinued in two, escalated in one, an initiated in another; in one an antiviral was administered. Conclusions: NGS may become a valuable addition to infectious disease diagnostics in cases of pediatric SIRS. However, NGS has not yet been validated as a diagnostic method in pediatric as a diagnostic method in pediatric patients and results should therefore be interpreted with caution. Multi-center NGS evaluation studies are currently being planned.