During the period from May 1, 1994 till December 31, 1997 at the First and Second Departments of Gynaecology and Obstetrics Masaryk University Brno 311 neonates with birthweights from 500 to 2000 g were born. A retrospective study was made comparing neonatal results of three methods of prenatal induction of maturing of surfactant in premature neonates. The first group was without treatment, in the second group only betamethasone was administered and in the third group betamethasone and thyrotropin releasing hormone (TRH). The neonates were divided into three body weight groups: 500-999 g, 1000-1499 g and 1500 g and more. The most favourable results with administration of betamethasone and TRH were obtained in the group weighing 500-999 g. This pertained to the smaller number of post-partum administration of surfactant, reduction of the oxygenation index and period of artificial pulmonary ventilation. IVth grade RDS and other complications in the child. In the group of neonates weighing 1000-1499 g administration of betamethasone and TRH had a positive effect only on the oxygenation index and grade of RDS. In the group of neonates with weights above 1500 there were no statistically significant differences between the described three groups. It may be concluded that the greatest effectiveness was achieved by a combination of betamethasone and TRH in neonates weighing 500-999 g, this combination was less effective in the group weighing 1000-1499 g and without effect in those weighing 1500 g or more.