Ultrasound technology is always connected to possible artefacts. Since introduction of ultrasound technology the knowledge of those artefacts is eminent to avoid misinterpretations. It is important to know that with the introduction of new ultrasound technology the possibility of artefacts are rising.Whereas artefacts initially were limited to B-mode sonography, every technological step (colour Doppler sonography, contrast enhanced sonography) comes with a range of new artefacts. This article is written to explain the technological basics of ultrasound artefacts and provide the reader with examples in daily practice and how to avoid them.