ABSTRACT.Thirty‐six babies below 1500g birth weight with patent ductus arteriosus were treated orally with indomethacin, for symptomatic reasons on 30 occasions and prophylactically on 44. Closure was significantly more frequent before 12.5 days of age and when treatment was given with 48 hours of development of clinical signs. Independently of age at treatment it was five times more successful when given within 48 hours of signs developing than when given later. Babies below 1000g birth weight responded as well as those above. Responsiveness did not appear to depend on individual idiosyncrasy. The approach described was aimed to minimise the contribution of a patent ductus to the dangerous recurrent apnoea of the very low birth weight infant.The use of indomethacin in the patent ductus arteriosus (PDA) of prematurity has been widely reported1,2. The lesion has a close relationship both to the degree of immaturity and to the presence of hyaline membrane disease (HMD)3–5. Reports in the literature deal mainly with this combination. However, it is also common in babies of very low birth weight who do not have HMD.Pharmacological treatment has been emphasised as a first line in management6,7, and evidence suggests it is more likely to succeed when given earlier rather than later after birth8. The published indications for treatment remain broadly those of deteriorating symptoms for which ligation might have otherwise been recommended. The present report compares that approach with treatment at an earlier st