RÉSUMÉDans l'industrie nucléaire française, les doses engagées après inhalation de radionucléides sont généralement évaluées à partir de mesures biologiques dont l'analyse peut permettre de remonter (démarche ascendante) à l'incorporation initiale puis à la dose par application de la dose par unité d'exposition (DPUI ABSTRACT Uncertainties in exposures, contamination level and doses after inhalation of actinides.In France, after occupational exposure to radioactive aerosols, committed doses are currently calculated by an ascending approach from biological data to estimate the initial contamination using dose per unit intake (DPUI). Specific DPUI can be calculated depending on the contamination. This paper is an overview on uncertainties in exposure level, biokinetics of radionuclides and doses after inhalation exposure to aerosol containing actinides. Data reported in the literature and those obtained in studies which are still in progress are described. A comparison of the uncertainties has been done after an ascending and a descending approach. In this later case, aerosol deposition within the respiratory tract is estimated from air sampling at the work place (estimate of the activity of the aerosol). The largest uncertainties were calculated after a descending application of the models. The results here reported pointed out the need of the knowledge of the uncertainties for