Abstract. The creation of 2D ultrasound mosaics is becoming a common clinical practice with a high clinical value. The next step coming along with the increasing availability of 2D array transducers is the creation of 3D mosaics. In the literature of ultrasound registration, the alignment of multiple images has not yet been addressed. Therefore, we propose registration strategies, which are able to cope with problems arising by multiple image alignment. Among others, we use simultaneous registration which urges the usage of multivariate similarity measures. In this paper, we propose alternative multivariate extensions based on a maximum likelihood framework. Experimental results show the good performance of the proposed registration strategies and similarity measures.