The aim of our study was to measure the basal serum cortisol concentration immediately after birth and to determine its association with perinatal factors and clinical outcomes in very low birth weight (VLBW) infants. Basal serum cortisol level was obtained within one hour after birth in inborn VLBW infants. The association between the basal serum cortisol level and perinatal and clinical outcomes was analyzed by comparing the groups with high versus low cortisol levels. In total, 80 infants were included. The median concentration of basal serum cortisol was 167 nmol/L with an interquartile range of 98-298 nmol/L. The basal serum cortisol concentration positively correlated with elapsed time from the last betamethasone dose. Low serum cortisol concentration was associated with antenatal corticosteroid therapy, low lactic acid level, and low leukocyte count at birth. Basal serum cortisol level was not associated with mortality and neonatal morbidities including hypotension and severe grade intraventricular hemorrhage. Both maternal corticosteroid therapy and perinatal distress may affect the basal serum cortisol concentration in VLBW infants early after birth.