IEM comprise a large class of genetic disorders, which are not rare. In our study, 50 patients aged 1month to 15 years, Mean 20.7months, Standard Deviation ±27.909, selected from ICU at Cairo University Children Hospital, were subjected to clinical & neurological examination, basic metabolic investigations & expanded metabolic screening using Tandem Mass Spectrometry (TMS). 3/50 (6%) proved to suffer from metabolic disorders. We have to maintain a high level of suspicion for diagnosis of IEM & we recommend screening of ICU patients, especially Neonatal ICU for IEM by TMS, as this will allow early therapeutic intervention.