Stroboscopy is well established as an essential diagnostic tool in the assessment of the vocal folds during phonation. This paper analyses the stroboscopic findings in 100 patients with a unilateral vocal fold paralysis. Reliable stroboscopic signals were only obtained in patients with the paralysed fold close to the midline. These patients seldom require surgery however, usually responding to speech therapy with laryngeal compensation giving a good voice. Most patients that require surgery have a large glottal deficiency, but in this series these patients did not give an adequate signal for analysis. Although useful in the assessment of the muscle tone of the paralysed fold, the influence of stroboscopy on the surgical treatment in this series was limited.