Bladder dysfunction (BD) is the most common autonomic disturbance in multiple sclerosis, but often overlooked and undertreated. The purpose of this longitudinal study was to explore the changes in the frequency of BD symptoms in MS cohort after a period of 3 and 6 years of follow-up, as well as to investigate the correlations between the presence of BD symptoms and both clinical characteristics and the health-related quality of life (HRQoL) at each subsequent point of estimation. The study population comprises a cohort of 93 patients with MS (McDonald's criteria, 2001). At each time point (baseline, and at the 3- and 6-year follow-up) of estimation, Expanded Disability Status Scale, Hamilton Rating Scale for Depression, Fatigue Severity Scale, Szasz Sexual Functioning Scale and HRQoL (measured by MSQoL-54) were assessed. The proportion of patients with at least one symptom of BD significantly increased over time, for both men and women (from 48.1% at baseline to 51.9% after 3 years and to 71.4% after 6 years of follow-up for males and from 45.5% at baseline to 50.0% after 3 years and to 66.7% after 6 years of follow-up for females). The most common BD problem was urgency of urination. The presence of BD was statistically significantly associated with higher level of physical disability, sexual dysfunction and HRQoL at each point of follow-up, for both men and women. Our results suggested outstanding frequency of BD in patients with MS, with increasing tendency over time.