The growth of weight, length and head circumference of 65 appropriate for gestational age (AGA) preterm infants and 85 full term controls has been studied longitudinally, with emphasis on growth velocity in the perinatal period. In comparison growth patterns of 51 small for gestational age (SGA) preterm infants have been analysed with respect to catch-up growth in relation to feeding practices. Weight gain of the AGA preterm infants is retarded until the corrected age of two months; their length remains below that of full term controls up to 21 months on average. Head circumference growth however is similar to intrauterine standards and from term agrees with that of the full term controls. Growth velocity is very high in the perinatal period and in the first months after term and decreases rapidly thereafter.