[en] Graded doses of injected ²²⁶Ra or ingested ⁹⁰Sr were given to 804 beagles in early life. The median survival times of the various irradiated groups at higher exposures were lower than the control value of 14.7 years. The ²²⁶Ra group with the highest total skeletal dose had a median survival of 4.5 years. For ⁹⁰Sr the highest group had a median survival of 2.2 years. Normal life spans were evident in treatment groups with average skeletal doses of <290 rads to the skeleton from ²²⁶Ra or of 2600 rads from ⁹⁰Sr. The life-shortening effects of ²²⁶Ra and ⁹⁰Sr are related to the tumors produced from the radionuclide exposure. The significant causes of death among the ²²⁶Ra-treated beagles were primary bone cancers, mostly osteosarcomas. Among dogs exposed to ⁹⁰Sr, significant numbers of deaths were from primary bone cancer, myeloproliferative disease, and squamous-cell carcinoma of the gingiva. In general, more of these effects were produced in the groups receiving higher doses and dose rates; at lower doses the effects, when present, appeared later than they did at higher doses. 9 refs., 6 figs., 4 tabs