Background: Bone metastatic disease affect a patient’s quality of life. Aim: Evaluating possible stratification factors affecting the efficacy of different schedules of zoledronic acid on SREs. Patients and Methods: A randomized, clinical trial at Zagazig university hospitals. 108 Patients were enrolled to receive zoledronic acid 4 mg (A and B groups=12 and 4 weeks, respectively) for 2 years. Results: Regarding age, tumour type, types of bone metastasis and number of bone metastasis, there was an insignificant difference between both groups. However, 3 monthly regimen of zoledronic acid gave better results in solitary than multiple bone metastases. Regarding pretreatment ECOG, there was an insignificant difference between between both groups. However, 3 monthly regimen of zoledronic acid gave better results in pre-treatment ECOG 1and ECOG 2 than ECOG 3. Conclusion: A 3-monthly regimen of zoledronic acid is more effective in management of solitary or few sites of bone metastasis, osteoblastic bony lesions and patients with good performance status. Recommendations: We recommend a larger sample size and the study should include a homogenous groups of patients so we can judge well on different stratifications factors that can affect efficacy of 3- monthly regimen of zoledronic acid.