Jaundice among Nigerian preterm infants under special care was studied to determine the incidence of clinical jaundice, the predisposing factors and outcome among those with significant hyperbilirubinaemia (SBR greater than or equal to 10mg/dl). The incidence of jaundice among 292 preterm infants over an 18-month period was 71.2%. The male: female ratio was 1:1.04. Of the 74 infants with serum bilirubin 10mg/dl or more, prematurity alone was the identified cause in 44 (59.5%), Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency and septicaemia were the only additional factors in 13 (17.6%) and 7 (9.5%) respectively, while multiple aetiological factors (prematurity, septicaemia and G-6-PD deficiency) were identified in six (8.1%) of the babies. Septicaemia was associated with higher mean bilirubin levels and the highest mortality. The two kernicteric infants in the study had septicaemia. Thus, the single most important cause of jaundice was prematurity. G-6-PD deficiency alone did not appear to increase the incidence and severity of hyperbilirubinaemia in this study. Septicaemia should be suspected and promptly treated in order to reduce mortality and risk of kernicterus among preterm infants with hyperbilirubinaemia.