The aim with this study was to explore how computer assisted simulation training mediates dialogue and if there is a relationship between group size and the groups´ dialogue patterns. It is based on two cases, one consisted of 18+18 dental students randomized into either collaborative 3D simulation training or conventional collaborative training, performed in triads. The other case consisted of 12 nursing students working in self-made pairs with the 3D simulator. The results showed that simulation training encouraged different dialogue patterns in comparison to the conventional training and that these characteristics were enhanced in the nursing students´ dyadic simulation training.