Transcutaneous bilirubinometry using the Minolta Airshield TcB was performed on 40 preterm VLBW Chinese infants during the first 7 days of life; altogether 614 observations were made on the forehead and sternum, respectively. A positive correlation between the TcB index and plasma bilirubin concentration was obtained on the forehead and sternum. Positive plasma bilirubin-TcB index correlations were also observed for each individual day. The plasma bilirubin-TcB index (forehead) regressions were fairly similar for the individual days and the combined overall regression except for 2 days (days 5 and 7). A slight improvement was observed when only bilirubin concentrations less than or equal to 200 mumol/l were evaluated. The intercepts were however different for individual days requiring correction factors to the combined overall regression intercept if the regression is to be used for the respective days. However, the plasma bilirubin-TcB index (sternum) regression for the individual days were significantly different one from another, and from the overall combined plasma bilirubin-TcB index (sternum) regression. This significant difference was still observed when only plasma bilirubin concentrations less than or equal to 200 mumol/l were evaluated. Hence, transcutaneous bilirubinometry has major limitations in preterm VLBW infants.