This issue of Primary Care: Clinics in Office Practice, guest edited by Drs. Maureen M. Okam and Aric Parnes, is devoted to Hematologic Diseases. Articles in this issue include: Anemia; Thrombocytopenia; Leukopenia and Pancytopenia; Leukocytosis and Leukemia; Polycythemia and Thrombocytosis; Eosinophilia; Thrombosis, Hypercoagulable States and Anticoagulants; Bleeding; Lymphoma; Plasma Cell Diseases; Transfusion Medicine; and Stem Cell Transplant.