Aim: Surgical patent ductus arteriosus (PDA) ligation is considered after failure or contraindication of medical treatment. Till now ligation of the PDA has been associated with low morbidity and mortality although recently concerns have been raised about the possible association of ductal clipping and neurodevelopmental abnormalities later in life. By means of near-infrared spectroscopy (NIRS), we analysed the changes in the cerebral tissue oxygenation index (TOI) and fractional tissue oxygen extraction (FTOE) at the time of clipping as well as after clipping. Method: Ten preterm infants with a symptomatic PDA who underwent surgical ligation were continuously monitored for heart rate (HR), mean arterial blood pressure (MABP), peripheral oxygen saturation (SaO(2)) and TOI from 1 h before up to 1 h after clipping. FTOE and haemoglobin difference (HbD) were calculated. Changes in parameters at 5 min after ligation represent the effect of the clipping itself whereas changes up to 1 h-post-clipping represent the post-clipping effect. Results: At the exact time of clipping, over the entire group, we found a significant increase in TOI of 2.9% (p = 0.037), in HbD of 12.5 mumol/l (p = 0.047) and in HR of 6.5 bpm (p = 0.012). FTOE significantly decreased by 0.02% (p = 0.013). One hour post-clipping, the cerebral and peripheral parameters were not significantly different from the control values before clipping. Conclusion: The ductal clipping in se has no negative effect on the cerebral oxygenation.