CDC has revised the classification system for HIV infection to emphasize the clinical importance of the CD4+ T-lymphocyte count in the categorization of HIV-related clinical conditions. This classification system replaces the system published by CDC in 1986 [1] and is primarily intended for use in public health practice. Consistent with the 1993 revised classification system, CDC has also expanded the AIDS surveillance case definition to include all HIV-infected persons who have + T-lymphocytes/µL, or a CD4+ T-lymphocyte percentage of total lymphocytes of <14. This expansion includes the addition of three clinical conditions—pulmonary tuberculosis, recurrent pneumonia, and invasive cervical cancer—and retains the 23 clinical conditions in the AIDS surveillance case definition published in 1987 [2]; it is to be used by all states for AIDS case reporting effective January 1, 1993.