The new technology of tandem mass spectrometry is having a significant impact on the diagnostics of inborn metabolic errors. One of the most important aspects of this new technology is the possibility of recognising a whole class of disorders within a single analytical step. Shall this powerful technology be applied to the screening of newborn babies? Careful evaluation of every single disorder that could potentially be identified is needed. In the following, I will present some considerations that concern glutaric aciduria type 1 (MIM 231670; glutaryl-CoA dehydrogenase deficiency).