We prospectively studied 30 older patients who had shunt surgery for symptomatic hydrocephalus and measured outcome using serial videotaping of gait, neuropsychological testing, and the Katz index of activities of daily living. Twenty-three patients improved and 7 did not. Using univariate analysis and the Fisher exact test, we found that the following variables were significantly related to outcome: (1) time B-waves present on 24-hour CSF pressure record; (2) anterior/posterior ratio on slice 4 of regional cerebral blood flow study; (3) duration of dementia prior to surgery; and (4) gait abnormality preceding dementia. The following variables showed a trend towards significance: (1) time CSF pressure greater than 15 mm Hg; and (2) scoring either pass or fail on the Multilingual Visual Naming Test. We conclude that several variables are significantly associated with surgical outcome in symptomatic hydrocephalus in the elderly and can be used in deciding whether to recommend surgery.