['To determine whether misperception of the subjective visual vertical (SVV) underlies balance difficulties in hemiplegic patients.', 'Descriptive study, using a convenience sample.', 'Department of physical medicine of a university hospital.', 'Thirty inpatients with hemiplegia after a hemispheric stroke during the 3 previous months.', 'Not applicable.', 'The SVV was tested while subjects sat in a dark room and were asked to adjust a luminous line to the vertical position. Mean SVV deviation and uncertainty, defined as the standard deviation, were calculated for 8 trials. Balance was assessed by the Postural Assessment Scale for Stroke (PASS) and while patients sat on a laterally rocking platform placed on a Satel force platform. The mean body position and the instability score (Lx), calculated as the length of the course of the center of pressure, were recorded. Functional outcome was also evaluated by the FIM instrument.', 'An abnormal SVV was recorded for 20 of 30 patients. Balance (ie, PASS, Lx) and FIM correlated significantly with SVV tilt (P<.001, P=.01, and P<.001, respectively) and with uncertainty (PASS, P=.006; FIM, P=.003).'] Does subjective visual vertical perception relate to balance in acute stroke?