BACKGROUND: Recently LDF has been used to investigate skin microcirculation in preterm infants usually at the heel, forearm or forehead. We assessed regional differences of skin blood flow by LDF, SUBJECTS: 20 stable preterm infants (11 m, 9 f) with median gestational age of 30 w (range 23 - 37), median birth weight 1170 g (range 565 - 2940), median age 19 days (range 1 - 98) were studied on three consecutive days. INTERVENTIONS: The LDF probe was applied to the upper chest wall (CW), forehead (FH), lower abdomen (A), forearm (FA) or lower leg (LL). LDF measurements were recorded every minute for 10 min together with heart rate, breaths/min and SaO2. RESULTS: The CW was chosen as the reference site and median LDF values set as 100%. Site comparison was made intraindividually. Heart rate, breaths/min and Sa02 remained stable. FH and A showed a wide variation with equal percentages below and above the CW reference. 74% of FA and 66% of LL measurements were below CW reference (median: FA: 49%, LL: 76%). CONCLUSION: LDF can be used for monitoring of microcirculation in preterm infants. FA and FL sampling sites have reduced microcirculation compared to CW.