Human immunodeficiency virus (HIV)‐associated neurocognitive disorders (HANDs) remain among the most common disorders in people infected with HIV, even in an era when potent antiretroviral therapy is widely deployed. This review discusses the clinical features of HANDs and the implications for more effective treatment. With the improved survival of individuals treated with antiretrovirals, comorbid conditions are increasingly salient, including particularly coinfection with hepatitis C and the effects of aging. This review attempts to answer why there appears to be a therapeutic gap between the salutary effects of antiretroviral regimens and normalization of neurological function. A second gap is found in the understanding of the pathophysiology of HANDs. This review addresses this and discusses the animal models that have helped to elucidate these mechanisms. Although triggered by productive HIV infection of brain macrophages, aberrant and sustained immune activation appears to play a major role in inducing HANDs, and may explain the often incomplete neurological response to highly active antiretroviral therapy. Novel therapies aimed at persistent central nervous system inflammation will be needed to close this gap. ANN NEUROL 2010;67:699–714