The examination involved 160 newborn infants during the first 4 days of life in the maternity hospital settings. The pain syndrome was studied in the course of prophylactic (vaccination, injection of vicasol) and diagnostic (blood sampling for phenylketonuria) procedures and in case of birth trauma (fracture of clavicle). For distinguishing a primary pain reaction from a pain response, in some infants preliminary analgesia with a cream based on local anesthetics was administered. Using a set of clinical tests, videorecord of motor activity, analysis of pain cry and pulse oxymetry, the authors show that a pain reaction in the neonate includes a totality of behavioral, motor and vegetative changes and depends on the character of the pain stimulus, gestational age of the neonate, the previous experience of pain appreciation, and also on the optimal course of the neonatal period.