Aim: To evaluate whether separation anxiety disorder (SAD) develops in the later life of the infants, who were separated from their mothers in relation to being in neonatal intensive care unit (NICU). Methods: A group of 57 children, ages over 6 years old who were cared in NICU has been evaluated retrospectively by using the SAD diagnostic scale which is adapted according to DSM-IV. Another age and sex matched 50 children who admitted to the outpatient unit were selected as control group. Results: We found that the scores and incidence of SAD were increased among children who were cared in the NICU and both were correlated with the duration of stay in the NICU. Conclusion: The NICU should be arranged to support the development of the baby. Families should be informed about the necessity of sustaining an early mother-infant interaction. By supporting mother-infant interaction, it will be provided that the baby will establish a more secure relation with his/her mother, develop more healthy and have less behavior problems in the future life.