This course provides a comprehensive overview of opportunistic infections (OIs) associated with Human Immunodeficiency Virus (HIV), with emphasis on their pathogenesis, clinical features, diagnosis, treatment, and prevention. Learners will understand how progressive immunosuppression increases susceptibility to bacterial, viral, fungal, and parasitic infections. The course covers common AIDS-defining illnesses such as tuberculosis, Pneumocystis jirovecii pneumonia, cryptococcal meningitis, toxoplasmosis, cytomegalovirus infection, candidiasis, and Mycobacterium avium complex. It also highlights the relationship between CD4 cell count and the risk of specific opportunistic infections, enabling learners to recognize disease patterns at different stages of HIV infection. Diagnostic approaches, including microbiological, serological, and molecular methods, are discussed alongside current treatment guidelines and prophylactic strategies. The role of antiretroviral therapy in preventing opportunistic infections and improving patient outcomes is also emphasized. By the end of the course, participants will be equipped to identify, diagnose, manage, and prevent opportunistic infections in people living with HIV, ensuring timely and evidence-based clinical care.