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