Acquired Brain Injury (ABI) is becoming an epidemic problem in our society, especially among older adults, being known as "the Silent Epidemic". People with ABI demand solutions in research that offer them with a relearning process such that they can recover not only their physical skills but also their cognitive abilities. In this context, the inherent characteristics of Ambient Intelligence (AmI), transparency and intelligence, have turned it into one of the best approaches to square up to the impairment that ABI can cause. As AmI proposes the development of context-aware systems that integrate different devices to recognize the context and act accordingly, these systems can react promptly to the needs of people with ABI while they carry out their rehabilitation process. Moreover, the explbitation of a Multi-Agent architecture emerges as a natural solution to develop AmI systems, since agents are reactive, proactive and exhibit an intelligent and autonomous behavior. Therefore, in this paper, a Multi-Agent architecture (MAS) for healthcare Aml systems is presented. It contributes to treat people with ABI by using specific devices to control the patient's movements and some physiological responses, such as the variation of the heart rate, during her rehabilitation process. In this way, the natural relationship between AmI and MAS is exploited. Finally, how this system is used to both design and execute therapies for people with ABI is presented.