Three-dimensional ultrasound examination was performed in 204 patients with a fetal malformation detected by conventional ultrasound. The patients were examined between 13 and 40 weeks of gestation. The ultrasound equipment used was a Combison 330 and a Combison 530 (Kretztechnik, Austria) with an abdominal Voluson sector transducer (3.5/5 MHz) (Kretztechnik, Austria). This ultrasound system can provide a high-quality three-dimensional surface or translucency image of fetal structures similar to that of a photograph or an X-ray image within seconds without an additional expensive work-station. Of the 204 patients examined with three-dimensional ultrasound, this technique proved advantageous in demonstrating fetal defects in 62% (127/204). In 36% (73/204), the three-dimensional technique gave the same information and in four fetuses with a cardiac malformation (2%), the three-dimensional technique was disadvantageous, due to movement artefacts during data acquisition. The technical advantages and problems of this three-dimensional technique are demonstrated.