In the past ten years, development of ultrasound diagnostic technology has been very fast, especially in the field of three- and four-dimensional ultrasound. The purpose of this arti­cle is to familiarise the reader with the physical background and possible applications of these technologies in gynecology and obstetrics. Different display modes of information (volumes) acquired using a three-dimensional ultrasound probe are described. Software integrated in three-dimensional ultrasound machines, which offer the possibility of measurement and analy­sis of acquired volumes are presented. The results of clinical studies which evaluated the usefulness of three-dimensional ultrasound at solving different problems in gynecology and obstetrics are also reported.