Objectives To identify in patients with idiopathic normal pressure hydrocephalus (iNPH) undergoing a cerebrospinal fluid (CSF) tap test (TT) for consideration of a ventricular peritoneal (VP) shunt: (1) gait and balance measures, which identify symptom change; (2) differences present between pre– and post–CSF TT scores between patients classified as responders and nonresponder; (3) ability of patients with iNPH to accurately quantify change in their gait and balance symptoms from a CSF TT. Design Prospective observational study. Post–CSF TT assessment was completed 2-4 hours post. Setting Tertiary referral neurological and neurosurgical hospital. Participants Patients (N=74) with iNPH receiving a 30 mL CSF TT for consideration of a VP shunt. Interventions Patients underwent a battery of gait and balance measures pre– and post–CSF TT and indicated their perceived change on a global rating of change (GRC). Patients deemed to improve and offered VP shunt insertion by a neurologist or neurosurgeon were labeled responders. Main Outcome Measures Performance oriented mobility assessment (Tinetti), Berg Balance Scale (BBS), timed Up and Go (TUG), 10-meter walk test (10MWT), GRC. Results Forty patients were classified responders, 34 nonresponders. Significant differences were identified for responders: Tinetti (3.88 points), TUG (3.98 seconds), 10MWT (0.08 m/sec), and BBS (5.29 points). Significant differences were found for nonresponders for the Tinetti (0.91 points) and BBS (2.06 points). Change scores for responders and nonresponders were significantly different for all tests between responders and nonresponders. GRC scores for gait (+2 for responders, 0 for nonresponders) and balance (+2.5 for responders, 0 for nonresponders) were both significantly different. Conclusions The Tinetti, BBS, and TUG can identify change in patients undergoing a CSF TT for iNPH. Patients appear to be able to accurately identify if change has occurred.