Functional capacity assessment is critical to evaluate risk profile and individual patient needs in the cardiac rehabilitation (CR) program. The goal is to ensure safe exercise training is provided with minimal risk entry. Such an evaluation will also support goal setting for the patient. Before the exercise training, a field test, a symptom-limited electrocardiographic or cardiopulmonary exercise test, is undertaken for prognostic, diagnostic, and therapeutic purposes, representing minimal, routine, and optimal testing standards, respectively. However, the need to perform a cardiopulmonary test is crucial to providing the data for meticulous exercise intensity prescription. In practice, the types of testing conducted by exercise professionals vary, depending on financial issues, local routine, and individual approaches. At the end of the supervised exercise training program, another evaluation should be performed to check individual progress, verify the goals and prescribe the long-term program. Functional assessment can be performed as follows: Cardiopulmonary exercise tests are recognized as the “gold standard” for direct measurement of cardiorespiratory fitness (CRF); however, due to their limited availability, electrocardiographic exercise testing remains the most common diagnostic tool in exercise laboratories. In such tests, however, the dedicated formulas estimate maximal oxygen uptake indirectly. Field tests should be performed as complementary to conventional testing, offering just approximate functional capacity assessment.