Reliable, real-time heart and breathing rates, plus core temperature, are key vital signs used in in many clinical and nonclinical settings to evaluate a person’s physiological status. Measuring these vital signs generally requires the superficial attachment of physically or logistically obtrusive sensors—such as rectal temperature probes—to individuals. Such sensors may cause skin irritation or adversely influence the person’s performance. Given the broad acceptance of ingestible electronics, MIT Lincoln Laboratory developed an approach that enables vital sign monitoring internally from the gastrointestinal tract--the EnteroPhone. Initial proof-of concept large animal (porcine) experiments demonstrated the feasibility of this approach. Implementing vital sign monitoring as a standalone technology or in conjunction with other ingestible devices has the capacity to significantly aid telemedicine, optimize performance monitoring of athletes, military service members, and first-responders, and provide an easy method for rapid clinical evaluation and triage.