Rai Classification separates chronic lymphocytic leukemia into low-, intermediate-, and high-risk categories, which correspond with stages 0, I & II, and III & IV, respectively:

• Rai Stage 0 patients are low risk and have lymphocytosis, a high lymphocyte count defined as more than 15,000 lymphocytes per cubic millimeter (> 15,000 /mm3).
• Rai Stage I patients are intermediate risk and have lymphocytosis plus enlarged lymph nodes (lymphadenopathy).
• Rai Stage II patients are also intermediate risk and lymphocytosis plus an enlarged liver (hepatomegaly) or enlarged spleen (splenomegaly), with or without lymphadenopathy.
• Rai Stage III patients are high-risk and have lymphocytosis plus anemia, a low red blood cell count (hemoglobin < 11 g/dL), with or without lymphadenopathy, hepatomegaly, or splenomegaly.
• Rai Stage IV patients are also high-risk but have lymphocytosis plus thrombocytopenia, a low number of blood platelets (< 100 – 103 /dL).