[en] This report presents a review of the external dosimetry of the ionising radiations for the protection of the human being. Looking at this topic, at first we are confronted with its diversity: the protection of the workers and the public against radiations, the medical exposures for radiotherapy, diagnosis and surgery, and the accidental situations. These aspects are often artificially separated so that the global comprehension becomes more difficult. We underline the points of convergence and the bonds which exist between the concepts of dosimetry adopted to deal with its different aspects. It also appeared useful to avoid proposing a dictionary of definitions copied in the reports of the international commissions, and adopting the formalism of the ICRU reports. This is why the definitions, when they are essential, are put in appendix. This text presents the reasons which led to the adoption of the system of quantity used today for the external dosimetry of the ionising radiations. After an introduction dealing with the general principle, the first chapter deals with the 'physical' quantities and the methods used for the determination of the national references. The second chapter, through the protection against radiation of the workers and the public, describes the bonds between the measurable 'operational' quantities and the non measurable 'protections' quantities which allow establishing the radiation protection limits and check that they are respected. The third chapter deals with the difficulties encountered for the measurements in area and personal dosimetry. The fourth chapter deals with the specificities of the medical exposures with the 'practical' quantities, the principle of optimisation and how radiotherapy is implemented. The fifth chapter briefly describes the case of the concerted exposures and of the accident. In conclusion, we analyse the needs and some potential new avenues of work for the metrology of the ionising radiations. (author)