Drug abuse and HIV infection are interlinked. From the onset of the HIV/AIDS epidemic, the impact of illicit drug use on HIV disease progression has been a focus of many investigations. Both laboratory-based and epidemiological studies strongly indicate that drug abuse may exacerbate HIV disease progression and increase mortality and morbidity in these patients. Increase susceptibility to opportunistic infection has been implicated as one of the major causes for this detriment. Furthermore, opioids are known to elicit prevalence of neurodegenerative disorders in HIV-infected patients. Numerous authors have delineated various molecular as well as cellular mechanisms associated with neurological complications in these patients. This review gives an overview of these findings. Understanding the mechanisms will allow for the development of targeted therapies aimed at reducing the progression of neurocognitive decline in the drug abusing HIV infected individuals.