RATIONALE: Monoclonal antibodies, such as rituximab, can block cancer growth in different ways. Some find cancer cells and kill them or carry cancer-killing substances to them. Others interfere with the ability of cancer cells to grow and spread. Drugs used in chemotherapy, such as fludarabine and cyclophosphamide, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Sometimes the cancer may not need treatment until it progresses. In this case, observation may be sufficient. It is not yet known whether giving rituximab together with fludarabine and cyclophosphamide is more effective than observation alone in treating chronic lymphocytic leukemia.