OBJECTIVE The purpose of this study was to determine whether maternal methadone dosage correlates with neonatal withdrawal in a large heroin-addicted pregnant population. METHODS A retrospective review of all maternal/neonatal records of pregnancies that were maintained on methadone therapy in our institution was conducted. After in-hospital stabilization, women were given daily methadone therapy under direct surveillance, with liberal dosage increases according to maternal withdrawal symptoms. Neonatal withdrawal was assessed objectively by the neonatal abstinence score. The average methadone dose in the last 12 weeks of pregnancy and the last methadone dose before delivery (cutoffs of 40, 60, or 80 mg) were correlated to various objective measures of neonatal withdrawal. RESULTS One hundred mother/neonate pairs on methadone therapy were identified. Women who received an average methadone dose of <80 mg (n=50 women) had a trend toward a higher incidence of illicit drug abuse before delivery than women who received doses of >/=80 mg (n=50 women; 48% vs 32%; P=.1). Women who received an average methadone dose of <80 mg had similar highest neonatal abstinence score, need for neonatal treatment for withdrawal, and duration of withdrawal compared with women whose condition was maintained with dosages of >/=80 mg (score, 11.1 vs 11.5; 68% vs 66%; and 13.3 vs 13.6 days, respectively; all P>.5). For all cutoffs that were used for high versus low dose and for both the average and last methadone dosage analyses, neonatal withdrawal was similar. CONCLUSIONS The maternal methadone dosage does not correlate with neonatal withdrawal; therefore, maternal benefits of effective methadone dosing are not offset by neonatal harm.