The purpose of this study was to determine if endoscopic and stroboscopic parameters of voice were normal between attacks of paradoxical vocal fold dysfunction (PVFD). Fifty adults (38 females, 12 males) and 54 adult controls (40 females, 14 males) were examined via endoscopy with and without stroboscopy. Endoscopy indicated paradoxical adduction of the folds during the respiratory cycle of all 50 participants with PVFD, although they were asymptomatic. Atypical laryngeal configurations were observed including abnormality of the anterior-posterior dimension and ventricular fold medialization in both groups of subjects. Stroboscopy demonstrated abnormalities including unstable zero phase, decreased amplitude of vibration, decreased mucosal waves, and phase asymmetry primarily for the PVFD subjects alone. Results indicate that persons with PVFD demonstrate subtle laryngeal abnormality endoscopically and stroboscopically when dyspnea is not reported. This supports the hypothesis that PVFD is not episodic but exists as a continuum of laryngeal instability that may, due to various precipitating factors, be exacerbated to breathing attacks.