Virtual worlds are based on a virtual reality technology, which allows three-dimensional realistic situations within a digital environment. The study framework is based on the Activity Theory and the model of Serious Games. These frameworks emphasize the interrelationships between the virtual worlds’ various components, including user activity, training design, and their formal definition as Serious Games. This study examined the teaching and learning characteristics which take place in three-dimensional virtual world environments (3DVW) and focused on a training pilot for emergency medical personnel of the Israeli First Aid medical teams (IFA). Semi-structured interviews were conducted through videoconferencing with 27 volunteers and employees of the IFA who participated in 3D virtual worlds training simulations. These interviews provided an understanding of their training experience in virtual worlds in general and the various medical simulation experience in particular. The findings showed that learning effectiveness was the main added value in immersive 3D virtual worlds training. The VW simulator has the ability to make learning more efficient and results in improvement and acquisition of professional skills in medical teams with an emphasis on following medical protocols. In addition, the virtual environment can enhance motivation and enjoyment in the context of medical training. Moreover, the virtual environment enables safe practice of complex medical procedures. These findings strengthen the positive trend of 3D virtual worlds technology implementation in medical training.