Objective: To evaluate the functional results obtained after voice therapy in patients with unilateral vocal fold paralysis caused by different aetiologies.Design: Prospective analysis of the outcome of unilateral vocal fold paralysis cases treated at our speech and language rehabilitation service from November 2003 to January 2006. Thirty cases underwent behavioural treatment, between two and six weeks after unilateral vocal fold paralysis onset. A multi-dimensional assessment was carried out before, immediately after and six months after treatment.Results: After behavioural therapy, the prevalence of complete glottal closure increased significantly (p < 0.05). Subjects' pre-therapy mean values for jitter, shimmer and noise-to-harmonic ratio were statistically significantly different from those taken both immediately and six months after treatment (p < 0.05). The mean values for voice turbulence index significantly improved only six months after therapy (0.08 vs 0.04). At both post-treatment assessments, voice range profile analysis showed a significant decrease of lowest voice frequency and a significant increase of the number of semitones (p < 0.05). Mean values for grade, instability, breathiness, asthenia and voice handicap index scores were significantly decreased both immediately and six months after treatment, compared with pre-treatment values (p < 0.05).Conclusions: Early voice therapy may enable significant improvement in vocal function, allowing the patient to avoid surgery.