Motor functioning of 38 infants, 15 exposed in utero to methadone, was assessed on Brazelton Neonatal Behavioral Assessment Scale with Kansas Supplements (NBAS-K) (Items: General Tonus, Motor Maturity, Activity, and Tremulousness) at 1 day, and at 4 months on Bayley Infant Behavior Record (IBR) (Items: Tension, Activity, Interest in Body Motion, Gross Coordination, and Fine Coordination). At 4 months, methadone infants generally showed a profile of poorer motor coordination, greater tenseness and interest in body motion, and higher activity level than did non-methadone infants. Guttman's Multidimensional Scalogram Analysis (MSA) of the 5 IBR motor-item profiles showed that a line can be drawn that almost perfectly discriminates the methadone and non-methadone infants by their joint performance on these 5 variables. A scatterplot of each infant's sum scores of the Brazelton versus IBR motor items revealed a significant correlation between 1-day and 4-month motor functioning. Methadone infants showed poorer motor functioning at both ages. This analysis of behavioral continuity again revealed an almost perfect discrimination between the two groups.