The effects of obstetrical medication on neonatal behavior were studied using a sample of 64 Israeli infants from medicated and non-medicated mothers. Most medicated mothers received a base dose of 75 mg. of Meperidine plus a base dose of 25 mg. of Phenergan. Other drugs used included Demerol, Valium, Butalgan, Pitocin, Pantopon, Trilene, Naline, and Torecon. Few significant behavioral differences (as measured by the Brazelton Neonatal Behavioral Assessment Scale) were detected in the first. month of life, and at 3 months of age there was no difference in performance on the motor and mental scales of the Bayley Scales of Infant Development. Comparative analyses using samples of American and Uruguayan infants and additional data from other studies of American newborns led to the conclusion that light levels of obstetrical medication do not appear to have significant effects on neonatal behavior. It is noted, however, that this conclusion may well be qualified by some initial population differences, by the measurements commonly used in the studies reviewed, and possibly by critical cut-off points dividing the levels of medication that will and will not affect neonatal behavior. It is recommended that, until more is known, mothers should use as little obstetrical medication as possible. A number of tables are included. (Author/MS)