In full-term newborns, transcutaneous estimation of serum bilirubin (SB) is reliable. However this method has not been validated in very preterm infants. Aim: Our objective was to investigate the accuracy of transcutaneous bilirubinometry (TcB) in preterm newborns with a gestational age (GA) < 30 weeks. Methods: This prospective multicenter study included 167 preterm neonates with a GA<30 weeks in three neonatal intensive-care units. Total SB determination was combined with TcB measurement with a BiliChek® analyser. Differences between the two results were related to several clinical data (gender, GA, modus of delivery, cause of premature birth, low birth weight, skin colour, phototherapy, infection, mode of ventilation and concomitant treatments). Results: One hundred and sixty seven newborns were included; 481 pairs of TcB-SB were analysed. Mean GA was 27.6 ± 1.6 weeks (extremes 24-29.9) and mean birth weight was 985 ± 248g. There was a significant correlation between TcB and SB (r=0.807; p<0.0001). TcB overestimated SB by 44µmol/l on average. TcB had a 96% sensitivity and a negative predictive value (NPV) of 98%. The specificity was 58% and positive predictive values 38%. The analysis was then subdivided in three periods: day1-day3, day4-day7, and day8-day15. The NPV was greater than 95% at all times (100%, 96% and 99% respectively). TcB sensibility was maximal on the first period (100%). TcB-BS discordance for establishing the indication of phototherapy was significantly greater during the first two periods (46% and 40%) than during the third period (19%). No risk factor was significantly associated with TcB-BS discordance throughout the 3 periods. By limiting the BS dosages to the cases of positive TcB results, the number of blood samples could be reduced by 55% overall, and by 80% on the third period. Discussion: TcB value was not sufficient to establish an indication for phototherapy but a TcB under the phototherapy limit had a very strong NPV and could warrant the absence of requirement for blood sampling. Conclusion: In preterm newborns <30 weeks of GA, TcB correlation with SB is good, with a tendency of BS overestimation by TcB. Due to its excellent sensibility and NPV, a TcB under the phototherapy threshold could eliminate the indication for blood sampling and treatment, as is actually the case for term newborns.