Abstract. OBJECTIVE: In this study, we validated the use of the FORE-SIGHT® (CAS Medical Systems, Branford, CT USA) tissue oximeter monitor on abdominal tissue oxygenation in infants ≤4 kg using a stool-interference compensation algorithm. STUDY DESIGN: A total of 40 neonates with an umbilical venous catheter (UVC) were enrolled in this study. We measured abdominal tissue saturation (StO2) values using FORE-SIGHT, and compared to a Reference StO2 value derived from weighted co-oximetry values from the UVC and pulse oximeter measurements. RESULTS: There was a strong correlation between NIRS calculated StO2 measurements when compared with the reference StO2, with an overall bias (sd) of −0.77 (5.06)% and a concordance correlation coefficient (CCC) of 0.789. CONCLUSION: Data from this validation study suggest that the FORE-SIGHT monitor, which compensates for the optical properties of stools in neonates, can yield accurate measures of abdominal tissue oxygen saturation.