<p>Newborn bloodspot screening (NBS) programs aim to identify babies at risk of developing serious conditions where an effective preventive or ameliorative intervention is available in infancy or early childhood. In recent decades, new testing technologies have been introduced into NBS to expand the number of screened conditions. This now also includes the possible introduction of genomic sequencing. Those who support genomic newborn screening (gNBS) do so on the rationale that a wider range of treatable conditions will be able to be screened for, and that gNBS will enable more equitable communication of actionable information to families. However, significantly increasing the number of conditions screened for may also increase expectations of screening coverage. Within a context of increased expectations of conditions being detected via gNBS, there is also the potential for actual or perceived ‘missed cases’, a situation where a newborn has (or will soon develop) a genetic condition that was not detected on screening. In this paper, we consider legal and ethical issues pertaining to missed cases in gNBS. We argue that certain missed cases in gNBS constitute neither a legal nor moral harm, especially where gNBS is delivered within a systematic screening program rather than via a commercially marketed test. However, should gNBS be introduced, engaging with key interest-holders such as parents and policy-makers will be vital to ensure that the scope and limitations of gNBS are both appreciated and accepted, and that public trust in this important population screening program is maintained.</p>