Amniotic fluid total lipids (T.L.), lipid phosphorus (L.Ph.), phospholipids (Ph.L.), total cholesterol (T.Ch.), total proteins (T.P.) and inorganic phosphorus (I.Ph) were determined in a number of high risk pregnancies and compared to parallel data obtained for full term normal pregnancies. Amniotic fluid T.L., L.Ph., Ph.L. and T.Ch. were significantly decreased in diabetic and toxaemic cases. The decrement in L.Ph. and Ph.L. was more pronounced in diabetic and toxaemic mothers who delivered either still-births or neonates suffering from RDS or in cases of intrapartum death. The L.Ph. and Ph.L. were increased in case of toxaemic mothers who delivered living neonates with no RDS. In spite of the increase in T.Ch. in the same cases; the ratio of T.Ch to T.L. was constant except in cases with prolonged intrauterine foetal death where it was increased.