Aim: To compare motor performance in supine position at the age of 4-months corrected age (CA) in very preterm (VPT) infants cared for in a neonatal intensive care unit (NICU) before and after the implementation of the Newborn Individualized Developmental Care and Assessment Program (NIDCAP). Methods: Assessments of motor performance in supine position according to level of motor development and quality of motor performance were made, using the Structured Observation of Motor Performance in Infants (SOMP-I). Subjects: VPT infants cared for in a NICU at a Swedish university hospital before, Group A (n = 68), and after, Group B (n = 58), the implementation of developmentally supportive care based on NIDCAP. Results: The infants who were treated after the introduction of NIDCAP showed higher level of motor development in the arms/hands and trunk. No significant group differences were noted in total deviation score for the respective limbs, but lower frequency of lateral flexion in head movements, extension-external rotation-abduction, extension-internal rotation-adduction and varus and valgus position in the feet was found in the NIDCAP group, compared with those treated before the introduction. Conclusion: The infants who were treated after NIDCAP care had been implemented showed a higher level of motor development in arms/hand and trunk and fewer deviations in head, legs and feet at 4-months CA than infants treated before NIDCAP implementation. The observed changes may be due to NIDCAP and/or improved perinatal and neonatal care during the studied time period.