Physical fitness represents one of the several facets of sports and physical activity which can have, on the short and long terms, definite influences on the health and the well-being of children and adolescents, as well as adults. The measurement of physical fitness raises several conceptual, methodological and technical problems which explains why surveys including such measures have been scarce until recently. In the first section, this review brings up the main methodological problems linked with fitness measurement: validity, reproducibility, reliability, normalization and standardization. The next section describes the various components of physical fitness, that is: endurance, muscular strength, agility, coordination and body composition. The paper then reviews the main test batteries available for children and adolescents and concludes on the utilization of such batteries in the future, either in the area of research (the relations between physical fitness and physical activity, psychomotor development, health of the individuals both present and future) or of individual and collective assessment of physical fitness.