The authors stress the importance of rhythmometry, thanks to which the time course and other peculiarities of any biological phenomenon can be evaluated by obtaining serial measurements, objectively quantifying their characteristic features, and working out special models with the aid of computers. Of special interest, particularly for the evaluation of reference standards, is autorhythmometry (AR), to be used at least for certain variables. This is the method by which each subject studies himself, performing a certain number of measurements in the course of the day (or month or year) of his body temperature, blood pressure, cardiac rhythm, grip strength, etc. In AR, the subject takes an active part in the study of his condition of health and it has been shown that in the majority of cases these measurements are done with the utmost accuracy and precision, providing that the purpose of the operations to be performed has been adequately explained. The wide spread use of AR, during more of less extended periods in a lifetime, would permit the assessment of the normal situation for each individual and thus offer the possibility of diagnosing any disorder at its very being; it would thus be of great prophylactic value. The authors refer to the example of arterial blood pressure; widely different values for the normal levels can be found in the texts of different authors. They also show that a certain pressure may be normal for a given subject at a certain time of day and be a sign of illness for another subject, or even for the same subject at a different time. The authors suggest the introduction of AR in the curriculum of secondary schools and into the routine for outpatients and inpatients. This practice would increase the availability of information on public health at a lower cost.