A Study to Assess the Effect of CellCept (Mycophenolate Mofetil) and Reduced Corticosteroids in Controlling Symptoms of Myasthenia Gravis

Inclusion Criteria: * adult patients 18 to 80 years of age; * diagnosis of myasthenia gravis; * history of myasthenia weakness involving more than ocular (ie eye) or peri-ocular muscle; * duration of myasthenia gravis symptoms (including ocular symptoms) \<=10 years; * prednisone dose \>=20 mg/day (or equivalent alternate-day dose) for \>=4 weeks. Exclusion Criteria: * female patients who are pregnant, breastfeeding, or lactating; * regularly scheduled plasma exchange (PE) or intravenous immunoglobulin (IVIG) treatment, or PE or IVIG treatment within 2 weeks prior to randomization; * any prior clinically significant use of CellCept or other immunosuppressive therapy (except corticosteroids), or within 8 weeks prior to randomization.