Zoledronic acid is an efficacy-proven bisphosphonate used in the patients who develop bone metastasis. In our study, we planned to evaluate side effects occurring in the patients who receive zoledronic acid. The records of a total of 5.482 patients diagnosed with solid tumor who were admitted to oncology out-patients' clinic between January 2001 and January 2007 were scanned. It was found that 256 patients received zoledronic acid. Zoledronic acid is administered in 4 mg doses for a period of 15 minutes as intravenous infusion once in 21/28 days. Side effects such as hypocalcemia, symptomatic hypocalcemia, impairment in renal functions and osteonecrosis of the jaw, were evaluated retrospectively. Zoledronic acid was administered due to bone metastasis in 248 patients, malign hypercalcemia in 6 patients and ostoporosis in 2 patients. Four patients (1.5%) were diagnosed with jaw osteonecrosis, 22 patients (8.5%) were diagnosed with hypocalcemia, 19 patients (7.4%) were diagnosed with impairment in renal functions, and 2 patients were (0.7%) diagnosed with symptomatic hypocalcemia. Zoledronic acid is a bisphosphonate which has been proven to reduce complications which may develop depending on the bone metastasis, such as pathological fracture, spinal chord impression andhypercalcemia. On the other hand, side effects may occur in the patients receiving zoledronic acid. It will be appropriate to inform the patients who are planned to start administering zoledronic acid of the benefits to be obtained and the side effects to take place.