The deviations of radiation damage (in the case of metals usually monitored by the residual electrical resistivity) from proportionality to the irradiation dose have so far been analysed almost exclusively in terms of extensions of models originally developed for small doses. The present theory considers the opposite limit, i. e. the quasi-saturated state. It is argued that at high doses the Lück-Sizmann effect may result in a self-organization of clusters of vacancies and self-intersititials, forming a heterogeneous froth. Possible structures of this froth and its effect on the electrical resistivity of metals are discussed. The model is shown to account for the dependence of the “saturation resistivity” on the nature of the irradiation as well as for several other hitherto poorly explained observations. Among them are the electrical-resistivity variation induced by high-dose irradiation with heavy ions, the amorphization of certain alloys by high-dose electron irradiation, and the occurrence of ordered arrays of stacking-fault tetrahedra afterin-situirradiations in high-voltage electron microscopes.