Obstetric and neonatal data were collected on 934 preterm deliveries in 11 Italian centres in 1980, 1985 and 1986. Therapeutic regimens for prevention of respiratory distress syndrome (RDS) were applied in 42% of the cases in 1980, 32% in 1985 and 42% in 1986. Prevention was made in most cases with corticosteroids, although their use fell progressively from 94% in 1980 to 74% in 1986. A combination of two substances was used in a percentage of cases varying from 5 to 10% in all three years. In 903 non-malformed infants, the overall incidence of RDS was not significantly different in cases in which pharmacological prevention was attempted compared with cases without prevention. The only factors significantly affecting the incidence of RDS were gestational age, birth weight and Apgar score.