Objective: To analyze patients with a confirmed voice disorder in order to identify patterns regarding age, gender, and occupation compared to the general public. To explore effects of voice therapy according to the Voice Handicap Index (VHI) score pre- and post-therapy in relation to the number of sessions, age, and gender. Design: Prospective cohort study. Materials and methods: This study was conducted as a collaborative project between Linkoping University and hospitals in the south-east health care region in Sweden. Six voice clinics participated by asking their patients voluntarily to complete the Swedish version of the VHI at the beginning and end of therapy. Results and conclusions: The two most prevalent diagnoses were dysphonia (43%) and phonasthenia (25%). Among the working population, the three most common occupational fields were education, health care, and child-care. The majority of the patients were women (74.3%), and the mean age of all patients was 55 years. A significant improvement in VHI scores was found after therapy, with an average decrease of 19 median points in total score and a substantial effect size (0.55). The number of sessions did not significantly correlate with the mean VHI score difference but had a weak correlation to the start and end scores. Increasing age correlated with a higher median VHI score both at the start and end of therapy but did not affect the average decrease between the two measurements.