We previously reported that platform stabilometry was effective in evaluating the condition of patients with vestibular neuritis. In the present study, we increased the patient population (n = 31) and followed them up for long-term (253.5 +/- 36.5 days after admission) to determine factors influencing prognosis. We examined the stability of patients with vestibular neuritis using platform stabilometry at 5 time points: P1, (5.3 +/- 0.7 days after admission); P2, (22.2 +/- 1.2 days); P3, (73.2 +/- 2.5 days); P4, (159.2 +/- 9.2 days); and P5, (258.3 +/- 23.5 days). For some elements--the total length of locus and the area of surroundings with open or closed eyes--the total length of locus with open eyes decreased significantly (P<0.05) following disease amelioration. Important factors for improving elements of platform stabilometry in patients with vestibular neuritis were age, presence of upper respiratory infection, and the duration of nystagmus.