Dengue fever, unlike most other arboviral diseases, does not usually cause encephalitis. However, neurologic symptoms with poor prognosis have been regularly reported, mostly in Asian children affected by the severe dengue hemorrhagic fever/dengue shock syndrome, and attributed to a non specific, anoxic or metabolic encephalopathy. Recently, first isolations of dengue viruses from CSF or brain tissue, have renewed this concept. We report 3 dengue fever cases with neurologic manifestations and favorable outcome. Occurrence in adult age, during classic (benign) dengue fever (2 cases), and neurologic sequellae (1 case) were the three outstanding features. We point out the proteiform expression of these neurologic changes and their low incidence rate (< 3% in our series of adult dengue fever). Although their pathogenesis is poorly understood, different mechanisms are suggested: encephalopathy (case n. 1), acute specific encephalitis (questionable in case n(o) 2), or post-infective encephalitis (case n(o) 3).