Triage is a process performed in an emergency department that aims to sort patients according to their need for care. When performed speedily and correctly, this process can potentially increase the chances of survival for a patient with serious complications. This study aims to develop a computer model, called UbiTriagem, which supports the process of triage using the concepts of web semantics and ubiquitous computing focused on healthcare. For evaluating the proposal, we performed an analysis of scenario-driven triage based on previously determined ratings. In addition, we conducted a usability evaluation in emergency department with the developed prototype with two user groups: nurses and patients. The main scientific contribution is the automatic triage assessment based on the gathering of patient data on mobile devices, performed automatically through the use of a reasoning technique in an ontology. The results for all evaluations were very positive. The automatic triage assessment has been assertive in 93.3% of the cases and, after adjustments in the model, in 100% of the cases. Regarding user satisfaction, we obtained rates of 98.7% and 96% when considering perception of utility and ease of use, respectively.