Selected normal pressure hydrocephalus (NPH) patients cannot be treated by shunt operation because of the procedure's high complication rate. We have treated cases in which prolonged clinical improvement of NPH was experienced after one or two lumbar punctures (LPs). We evaluated the predictors of prolonged improvement of NPH symptoms by repeated LP. Thirty-one NPH patients were retrospectively evaluated (age 72.5 +/- 5.8 years). Gait disturbance, urinary incontinence, and cognitive impairment were semiquantified. We divided the patients into three groups (non-responders, temporary responders, and prolonged responders) according to their responses after LP. We analyzed the characteristics of the groups. Gait disturbance (p = 0.046) and urinary incontinence (p = 0.040) scores and total NPH symptom score (p = 0.007) after cerebrospinal fluid drainage were more significantly improved in prolonged responders than in temporary responders. On multiple logistic regression analyses, total NPH score improvement was the only predictor of the prolonged responders (p = 0.03, odds ratio 0.148). Our study showed that some NPH patients could maintain favorable courses for at least 1 year after LP without shunt operation. Repeated LP could be an alternative treatment in selected NPH patients.