This is a multicenter, randomized trial to compare the safety and efficacy of two dosing frequencies of Cerezyme® in patients with Gaucher disease who are currently being treated with Cerezyme®.

Approximately 90 patients will be randomized in a 2:1 (q4 : q2) ratio to one of two treatment arms at up to 26 study centers worldwide. Patients will continue to receive the same total 4-week dose that they were receiving prior to study enrollment, however, they will be randomized to receive either their total 4-week dose in two infusions, one infusion every 2 weeks or their total 4-week dose in one infusion every 4 weeks. The randomization scheme will ensure a 2:1 balance between the every 4-week versus every 2-week infusion groups, respectively.

Inclusion Criteria:

• The patient must provide written informed consent prior to undergoing any study-related procedures.
• The patient has a confirmed diagnosis of Gaucher disease with a documented deficiency of glucocerebrosidase by enzyme assay
• The patient has been genotyped or will have genotyping performed within 3 months of study enrollment.
• The patient has been treated with Cerezyme for at least 2 years prior to study enrollment.
• The patient has been on a stable dose of between 20-60 U/kg every 2 weeks for at least 6 months prior to study enrollment.
• The patient is at least 18 years old.
• The patient has a hemoglobin value of ≥ 11.0 g/dL for women and ≥ 12.0 g/dL for men and a platelet count of ≥ 100,000 mm^3.
• The patient's liver volume is ≤ 1.8 x normal confirmed by MRI or CT within 6 months of randomization.
• The patient's spleen volume is ≤ 10 x normal confirmed by MRI or CT within 6 months of randomization.
• The patient has a serum creatinine < 2.0 mg/dL, an ASTand ALT < 2 x upper limit of normal and a total bilirubin < 2.0 x upper limit of normal.
• Female patients of childbearing potential must have a negative pregnancy test within 2 weeks prior to randomization into the study.

Exclusion Criteria:

• The patient is pregnant.
• The patient has evidence of neurologic or pulmonary involvement with Gaucher disease confirmed by medical history.
• The patient has evidence of current or prior bleeding varices or liver infarction requiring hospitalization confirmed by medical history.
• The patient has evidence of pathologic bone fractures, medullary infarctions, lytic lesions or avascular necrosis secondary to Gaucher disease confirmed by skeletal evaluation within 6 months of randomization.
• The patient has had a bone crisis (defined as pain with acute onset which requires immobilization of the affected area, narcotics for relief of pain and may be accompanied by periosteal elevation, increased white cell count, fever or debilitation of > 3 days) within 12 months of randomization.
• Patient has received an investigational drug within 30 days of the start of their participation in this trial. Patients may not receive any other investigational product throughout the course of the study.
• The patient has a clinically significant disease (with the exception of symptoms relating to Gaucher disease), including clinically significant cardiovascular, hepatic, immunologic, pulmonary, neurologic, or renal disease, or other medical condition, serious intercurrent illness, or extenuating circumstances that, in the opinion of the Investigator, would preclude participation in the trial or potentially decrease survival
• Patient has a medical, emotional, behavioral or psychological condition that in the judgment of the Investigator would interfere with the patient's compliance with the requirements of the study.