A research report submitted to the University of the Witwatersrand, Johannesburg in fulfillment of the requirements of the degree of Master of Medicine 2016/2017. / Background: The effect of HIV infection on the evolution of NCC constitutes a new area of interest. Purpose: To review the literature on the imaging appearances of NCC and HIV co-infection and compare it with our cases. Materialsand methods: Data from both published andlocal cases were analysed. HIV-infected cases were divided into “low” (<200 cells/mm3) and“high” (≥200 cells/mm3)CD4 groups. These groups were compared and the effect of treatmentwas evaluated. Results: Thirty-three cases were evaluated - 20of our, and 13 published, cases. The published cases had parenchymal brain cysts, whereas our cases had both parenchymal and subarachnoid cysts (p=0.0050). The published cases also had intra-axial cysts, whereas our cases had both intra- and extra-axial cysts (p=0.012). The published cases had predominantly cystic lesions, whereas our cases had both cystic and granulomatous lesions (p=0.019). There were no differences between cases with a CD4 count of <200 cells/mm3 and cases with a CD4 count of ≥200cells/mm3but, interestingly, 3% of the cases with a CD4 count of <500cells/mm3,compared with 50% of the cases with a CD4 count of ≥500cells/mm3,had racemose cysts. Conclusion:NCC is very prevalent in South Africa and may complicate the diagnosis and treatment of patients with concomitant HIV infection.Patients with a “low” CD4 count may present with atypical lesions, delaying the diagnosis of NCC. Early initiation of HAART may result in patients presenting with more classical symptoms and imaging appearances, thus improving outcomes. / MT2017