This issue of Clinics in Geriatric Medicine, guest edited by Drs. Thomas T. Yoshikawa and Dean C. Norman, is devoted to Infectious Diseases in Geriatric Medicine. Articles in this issue include: Host Resistance and Immunology of Aging; Clinical Features of Infection; Principles of Antimicrobial Therapy; Bacterial Pneumonia; Tuberculosis; Intraabdominal Infections; Infectious Diarrhea: Clostridium Difficile and Norovirus; Urinary Tract Infection; Herpes Zoster; Bone and Joint Infections; Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome; Infections in the Long-Term Care Setting; and Vaccinations.