We have retrospectively examined 94 evaluable patients with metastatic osteolysis from breast cancer (BC) and non-small cell lung (NSCLC) cancer, who received RT from Nov. 88 to Nov. 89.27 (15 BC and 12 NSCLC) were in treatment with Clodronate for at least 3 days from the beginning of RT; of the remaining 67 treated with RT alone, 31 had NSCLC and 36 BC. We have evaluated: increase in pain (IP) occurring on the first days of RT, percentages of complete pain relief (CPR) at the end of RT and 4-6 weeks after. A decreased occurrence of IP was observed more in NSCLC patients receiving RT + Clodronate compared to those treated with RT alone (33.3% vs 41.9%). Both at the end of RT and 4-6 weeks after, we registered a significant difference in the percentages of CPR in the RT + Clodronate group (40.7 vs 20.9 and 70.3% vs 53.7%). We believe the points of interest focused in this paper-greater precision in centering and defining the target volume, decreased occurrence of IP during the first days of RT, increase in percentage of CPR--need a prospective confirmation.