Objectives: The tight syndrome after open-heart procedures in neonates renders delayed sternal closure (DSC) a life-saving measure. The goal of this study is to analyze the risk factors that may predict the need for DSC. Methods: Between January 1991 and December 2000, 312 consecutive open-heart procedures in neonates (180 males, 132 females) were studied retrospectively. Median age was 11.9 days (range 1–30 days) and weight 3.63 kg (range 1.8–4.2 kg). The major pathologies were transposition of the great arteries (153), interruption of the aortic arch (IAA) (33), total anomalous pulmonary venous drainage (TAPVD) (24) and single ventricle (19). Two hundred and twenty-eight patients had profound hypothermia with circulatory arrest and 74 normothermic cardiopulmonary bypass (CPB), 195 had crystalloid cardioplegia and 111 blood cardioplegia. Median CBP time was 146 min (range 37–284 min) and aortic clamping 67.6 min (range 0–164 min). Two hundred and fifty-five patients had a continuous ultrafiltration and 57 had a modified ultrafiltration. The criteria for DSC were hemodynamic instability, deterioration of the central venous saturation, metabolic status and/or high ventilatory pressures. Results: One hundred and nineteen patients had DSC (38.12%). Median CBP time was 145 min (range 37–284 min) and aortic clamping time 67.6 min (range 0–164 min). Twenty-one patients (6.7%) needed reopening in the intensive care unit (ICU) during the first 24 h. Among the studied factors, the age below 7 days (P=0.014), the diagnosis of IAA and TAPVD (P≪0.05), CBP duration over 185 min (P=0.048), clamping time over 98 min (P=0.039) and central venous saturation below 51% P=0.024) were statistically significant risk factors. All the patients who had more than 106 min of clamping, more than 196 min of cardiopulmonary bypass or less than 47% of central venous saturation were either left opened or reopened in the ICU. Conclusions: Many of the factors thought to be associated with the need for delaying the sternal closure had no statistical significance as risk factors. On the other hand, the diagnosis of IAA or TAPVD, an age less than 7 days, aortic clamping more than 98 min, CPB time more than 185 min and a post-bypass central venous saturation less than 51% were statistically significant risk factors that could be used in predicting the need for delaying the sternal closure.