ABSTRACT.Free fatty acid (FFA), triglyceride (TG), total cholesterol (T‐C), VLDL + LDL‐C, HDL‐C and its subfractions were determined in 18 very low birthweight (birthweight: 1064 ± 179 g; gestational age: 28.7 ± 1.6 weeks, mean ± SD) preterm infants on postnatal days 1, 14, 28, 42 and 56 (data are given in mmol/l). FFA levels remained low throughout the study (day 1: 0.13 ± 0.09…day 28: 0.15 ± 0.06…day 56: 0.16 ± 0.06). TG levels increased significantly from day 1 to 14 and from day 14 to 28 (day 1: 0.61 ± 0.06, day 14: 1.14 ± 0.28, day 28: 1.70 ± 0.89), thereafter they remained unchanged. T‐C levels increased significantly from day 1 (2.29 ± 0.83) to day 14 (3.05 ± 0.71), continued to increase up to day 28 (3.34 ± 1.58), subsequently decreasing to the level of day 1 (day 56: 2.63 ± 0.87). More marked alterations were seen in VLDL + LDL‐C (day 1: 1.51 ± 0.70, day 28: 2.32 ± 1.34, day 56: 1.76 ± 0.74), whereas in HDL‐C it was HD