Clinical application of 80 patients treated with 89 Sr for metastatic bony pain was reported the toxic effet and dosage was also evaluated. Of the 17 cases with complete blood sample examination

7 cases with the dosage of 1.11—1.48MBq/kg showed no changes in leukocyte and platelet count. 10 cases with the dosage of 1.48—2.22MBq/kg showed slight decline 14% and 23% respectively in leukocyte and platelet count. 5—6 weeks after 89 Sr treatment. As to the pain relief 25 cases 31.25% complete pain free (grade 4)

34 (42.5%) are of significant pain decrease (grade 3)

13 (16.25%) are of slight pain decrease (grade 2)

8 (10.0%) are of no change or even pain aggravated (grade 1)

the total efficacy of 89 Sr was 90.0% and the significant efficacy (complete pain free + significant pain relief) was 73.75%. The optimal dose of our study was within the range of 1.11—1.48MBq/kg. Thereby

it was concluded 89 Sr was effective for relief of the metastatic bony pain.