Background and aim:   nowadays, comprehensive  developmental assessment of infants is highly considered. But, some assessments, especially those which use more manipulations on high risk infants, can cause more stress  on them. So sometimes it is necessary  to use one group of developmental assessments to predict another developmental aspect.  The aim of this study was to investigate the relationship between scores of behavioral scale and  motor performance.
Materials and methods:   In this  cross-sectional study that was conducted in neonatal intensive care unit and pediatric clinic of Shahid  Akbarabadi hospital, Tehran, 50 under 2 months low birth weight infants after met inclusion criteria were selected via convinence sampling method.  The Test of Infant Motor Performance (TIMP) and the Neonatal Behavioral Assessment Scale (NBAS) was used  for assessing motor performance and behavioral performance respectively. The TIMP consist of elicited and observational parts. NBAS was consisted  of habituation, social interaction, motor system, state organization, state regulation, autonomic system,  smile, supplementary items, and reflex items.
Results:  There was not any significant relationship between habituation part  of NBAS  and TIMP and also between autonomus system part  of  NBAS  and observational part of  TIMP (P<0.05).  Association between other variables was statistically significant (P>0.05).
Conclusion: Some items of behavioral assessment  can be used to predict  the motor performance in low birth weight infants.