Purpose: To investigate the practice of obstetric ultrasound in Norway before and 2 years after a consensus conference recommending routine screening. Material, method: Two national representative materials sampled with a 2-year interval are compared. Results: The average number of examinations was reduced from 2.46 to 2.2 (p = 0.014). Obstetrical institutions practising screening examined their patient less frequently than non-screening institutions (2.10 vs. 2.75 times, p less than 0.001 whereas in 1986 the converse was the case. Conclusions: Screening has become more widespread, and a more rational practice has developed.