In a prospective study of 36 children who were extremely low birthweight (ELBW: < 1000 g) preterm infants and 36 matched full-term controls, differences were found in somatization at age 4 1/2 years. Only children who had been extremely premature, and thereby experienced prolonged hospitalization and repeated medical intervention in infancy, had clinically high somatization scores on the Personality Inventory for Children. The combination of family relations at age 4 1/2 years, neonatal intensive care experience, poor maternal sensitivity to child cues in mother-child interaction observed at age 3 years, and child avoidance of touch or holding at age 3, predicted somatization scores, prior to school entry. Due to the known higher incidence of actual medical problems among children with a history of extreme prematurity, the high somatization ELBW children were compared with the normal somatization ELBW children. There were no differences in prevalence of actual medical problems between the 2 ELBW groups, and the importance of maternal factors in relation to somatization was confirmed. Child temperament at age 3, but not personality at 4 1/2, was related to somatization. The etiology of recurrent physical complaints of no known medical cause appears to be a multi-dimensional problem. Non-optimal parenting may contribute to the development of inappropriate strategies for coping with common pains of childhood, or of chronic pain patterns, in some children who have experienced prolonged or repeated pain as neonates.