In this article the authors present a case of pathological neonatal jaundice resistant to phototherapy in a baby with a family history of Gilbert's syndrome and hereditary spherocytosis. Her presentation was ultimately explained with a diagnosis of both conditions, and required treatment with phenobarbitone. The authors discuss the mechanism by which Gilbert's syndrome results in hyperbilirubinaemia and its similarities with Crigler-Najjar syndrome. The presentation of hereditary spherocystosis in the neonatal period is also explored, as is the mechanism of exaggerated hyperbilirubinaemia when the two conditions co-exist.