BACKGROUND Acquired Immunodeficiency Syndrome (AIDS) was first described to occur in children in 1983. With experience of increasing number of cases of AIDS, pathologic lesions in various organs and tissues such as lungs, brain, G.I. tract, heart, blood vessels, lymph nodes, spleen, bone marrow, etc. became evident in autopsy and biopsy specimens. These pathologic lesions were classified into four groups based on known or suspected pathogenesis: 1) Primary lesions due to Human Immunodeficiency (HIV) infection itself (lymph nodes, brain, etc) 2) associated lesions related to direct or indirect sequelae of HIV infection (Opportunistic infections, PLH/LIP complex, etc) 3) lesions of undetermined pathogenesis, (cardiomyopathy, arteriopathy, thrombocytopenia, nephropathy, etc) 4) lesions of multifactorial pathogenesis (villous atrophy of intestine, thymic lesions, etc). In recent years the emphasis of pathologic study is on the reactive and neoplastic proliferative disorders. These disorders include nodal and extranodal lymphoproliferative lesions (such as myoepithelial sialadenitis, malignant lymphomas, etc), smooth muscle tumors (SMTs), Kaposi's sarcoma, Human Papilloma virus associated genital lesions and miscellaneous tumors. In a recent study, it has been shown that Epstein-Barr virus (EBV) may be related to the pathogenesis of SMTs. The most recently recognized lymphoproliferative lesions include those of mucosa associated lymphoid tissue (MALT) of salivary glands, lungs and tonsils. The MALT lymphomas in children with AIDS are responsive to therapy and tend to take an indolent clinical course. Therefore recognition of MALT lymphomas as a distinctive lesion in pediatric AIDS is of practical importance. In this view of increasing incidence of HIV and HPV infections in adolescent females seen in certain countries attention should also be focused on early detection of HPV related genital lesions so that their possible progression to intraepithelial and invasive cervical carcinoma can be prevented.