This booklet gives a convenient survey of the methods of radium dosimetry. Its title expresses at the same time the fact that the field is still in a developmental state and that this publication presents only the present situation without claiming final disposition of the problem. Radium dosimetry is discussed from two points of view; first, as what the author calls "relative" dosimetry dealing with the special distribution of radiation in the neighborhood of radium preparations and, second, "absolute" dosimetry. This is the investigation of the practicability of a unit of dosage and its realization. In the first part, on relative dosimetry, the ionometric method is discussed and the instruments described; the photographic biologic methods of radium dosimetry as well as the mathematical methods are also discussed. This chapter is concluded by a comparative investigation of these methods, in order to draw conclusions concerning the range of applicability of each.