<i>HNF4A</i>-associated CHI is very rare, and this particular case had a clinical phenotype quite different from that of previously described <i>HNF4A</i>-CHI cases.<h4>Conclusions</h4>This case series is one of few reports in the medical literature describing two IDMs with persistent recurrent hypoglycemia secondary to CHI, and a different clinical phenotype for <i>HNF4A</i>-associated CHI. This evidence concerns the gene HNF4A and congenital isolated hyperinsulinism.