The objective of this study was to describe the clinical features of cases hospitalized with West Nile virus (WNV) infections and identify clinical parameters that could potentially predict poor outcome (death). Retrospective medical chart reviews were completed for 172 confirmed cases of WNV infection hospitalized in the Houston, Texas, metropolitan area between 2002 and 2004. Of the 172 patients, 113 had encephalitis which resulted in 17 deaths, 47 had meningitis, and 12 had uncomplicated fever. Risk factors associated with progression from encephalitis to death were absence of pleocytosis in the cerebrospinal fluid, renal insufficiency, requiring intubation and mechanical ventilation, presence of myoclonus or tremors, and loss of consciousness. These findings can aid physicians in evaluating their patients suspected of WNV infection and determining outcomes in their patients with confirmed WNV neuroinvasive disease.