1. Successful treatment of the hemopoietic phase of the acute irradiation syndrome in dogs at the LD100 (400 r) dose is possible on an individual case basis with good nursing care.
2. The onset and rate of regeneration is related to the radiation dose. Partial regeneration with subsequent death occurs with a 550 r dose.
3. The control of infection during the critical period prior to regeneration appeared to be the limiting factor in successful treatment at the dose levels used in this study.