The distribution of morphine in various tissues of 6 addicted monkey fetuses and in 2 infants of drug-dependent mothers (IDDM) show that significant concentrations of the drug are in the gastrointestines (tissue plus content), liver, cerebellum, lungs, heart, spleen and thymus. The high concentration of morphine in the gastrointestinal tract may be secondary to the excretion of the drug through the bile or by the repeated swallowing by the fetus of amniotic fluid which contains morphine (1.9 .+-. 1.9 .mu.g/dl). Meconium taken from 2 IDDM shows a significant concentration of morphine for up to 2-3 days after birth. Meconium is a useful material to analyze postnatally for the diagnosis of neonatal narcotic addiction.