Inclusion Criteria

Inclusion criteria:

- Patients with histologically confirmed diagnosis of prostate cancer who have not yet
developed bone metastases

- Prostate cancer patients with a rise in PSA under hormone therapy.

PSA criteria:

- Patients who have undergone prostatectomy: any rise in PSA or

- Patients without prostatectomy: 2 consecutive rises in PSA levels relative to a
previous reference value, separated by one month. The first measurement must occur
one month after the reference value and must be above the reference value. The second
confirmatory measurement taken one month after the first measurement must be greater
than the first measurement.

- Previous chemotherapy or radiotherapy must have been performed ≥ 8 weeks prior to
study entry.

- Eastern Cooperative Oncology Group (ECOG) score of 0, 1 or 2 (patients that spend
less than 50% of time in bed during the day)

- Adequate liver function - serum total bilirubin concentration less than 1.5 x upper
limit of normal value

- Age: ≥ 18 years

- Patient has given written informed consent prior to any study-specific procedures.
Patients with psychiatric or addictive disorders which prevent them from giving their
informed consent must not enter the study.

Exclusion criteria:

- Prior treatment with a bisphosphonate

- Abnormal renal function as evidenced by a calculated creatinine clearance < 30
ml/minute.

- Corrected (adjusted for serum albumin) serum calcium concentration < 8.0 mg/dl (2.00
mmol/L) or ≥ 12.0 mg/dl (3.00 mmol/L).

- Patients with clinically symptomatic brain metastases

- History of diseases with influence on bone metabolism such as Paget's disease and
primary hyperparathyroidism

- Severe physical or psychological concomitant diseases that might impair compliance
with the provisions of the study protocol or that might impair the assessment of drug
or patient safety, e.g. clinically significant ascites, cardiac failure, NYHA III or
IV, clinically relevant pathologic findings in ECG

- Known hypersensitivity to zoledronic acid or other bisphosphonates

- Use of other investigational drugs 30 days prior to the date of randomization

- Known history or present abuse of alcohol or drugs

- Subjects who, in the opinion of the investigator, are unlikely to cooperate fully
during the study

- Current active dental problems including infection of the teeth or jawbone (maxilla
or mandibular); dental or fixture trauma, or a current or prior diagnosis of
osteonecrosis of the jaw (ONJ), of exposed bone in the mouth, or of slow healing
after dental procedures.

- Recent (within 6 weeks) or planned dental or jaw surgery (e.g. extraction, implants)

Other protocol defined inclusion/exclusion criteria may apply.