The aim of this study was to assess the influence of maternal methadone dosage on the severity of neonatal withdrawal. The charts of 67 drug-abusing mothers and their 70 infants were examined to determine documented patterns of drug usage and the severity of neonatal withdrawal. Of these, 40 women were on a methadone programme. There was a strong relationship between maternal methadone dose at delivery and severity of neonatal withdrawal as assessed by the Neonatal Abstinence Score, length of stay and duration of treatment. Children whose mothers received methadone had mean peak symptom scores greater than 10 whereas the group receiving no methadone had mean scores of less than 4 (p < 0.001). These effects tended to increase with increasing doses of methadone. Length of stay and duration of neonatal treatment showed highly statistically significant increases (p < 0.001) with increasing methadone dose. Maternal methadone dose appears to be strongly related to the severity of neonatal withdrawal.