This study will examine the safety and effectiveness of daclizumab (also called Zenapax or anti-CD25) in patients with Wegener's granulomatosis, a type of vasculitis (blood vessel inflammation). Wegener's granulomatosis can affect many parts of the body, including the brain, nerves, eyes, sinuses, lungs, kidneys, intestinal tract, skin, joints, heart, and other sites. Standard treatment is a combination of prednisone and a cytotoxic agent (a drug that interferes with cell growth), usually cyclophosphamide or methotrexate. However, many patients treated with this regimen have a disease relapse, and others cannot take these drugs because of severe side effects. This study will focus on the effectiveness of daclizumab in preventing disease relapse.