The objective of the study was to provide an epidemiological description of the use of ultrasound in obstetrics in Denmark. It was performed as a questionnaire study based on hospital records and patient interviews. All Danish hospital departments with delivery services (n = 57) participated in the study which, in total, comprised 2.268 women who gave birth to a child during a two week period in February 1990. The main results of the study are that women with an offer of screening had a significantly higher mean number of obstetric ultrasound examinations during pregnancy (1.8) than women without such an offer (1.3). Of the women without an offer of screening, 45% had an ultrasound examination on indication in the interval of 14-20 weeks of gestation. The study shows great regional variations in the use of ultrasound in obstetrics in Denmark.