Lungs are the most commonly involved organ by HIV/AIDS related diseases, and pulmonary infections are the main reasons for the increasing death rate from AIDS. Pathogens of HIV related pulmonary infections include parasites, fungi, mycobacteria, viruses, bacteria and toxoplasma gondii. According to international reports, pathogens have different geographical distribution, which is also closely related to the socioeconomic status of the region to produce varied AIDS related diseases spectra. For instance, in the United States, pneumocystis carnii pneumonia (PCP), tuberculosis and recurrent bacterial pneumonia (at least twice within 1 year) occur frequently in HIV infected patients. An international report published 10 years ago indicated that PCP is the most common and serious pulmonary opportunistic infections in HIV infected patients. Now its incidence has dropped with the application of antiretroviral treatment and preventive measures. PCP will continue to occur initially in patients who are aware of their HIV infection. In addition, HIV related viral and parasitic infections have been reported both domestically and internationally. In this section, the clinical manifestations and imaging findings of HIV related pulmonary infections are analyzed and discussed, which provide effective diagnosis basis, so as to reduce the incidence of HIV-related pulmonary infections.