Vocal folds undergo osmotic challenge by mouth breathing during singing, exercising, and loud speaking. Just 15 min of obligatory oral breathing, to dry the vocal folds, increases phonation threshold pressure (P[subscript th]) and expiratory vocal effort in healthy speakers (M. Sivasankar & K. Fisher, 2002). We questioned whether oral breathing is more detrimental to phonation in healthy participants with a history of temporary vocal attrition. The effects of a 15-min oral or nasal breathing challenge on P[subscript th] and perceived expiratory vocal effort were compared for participants reporting symptoms of vocal attrition (N = 18, ages 19-38 years) and normal controls (N = 20, ages 19-33 years). Postchallenge-prechallenge differences in P[subscript th](deltaP[subscript th]) and effort (deltaEffort) revealed that oral breathing, but not nasal breathing, increased P[subscript th](p greater than 0.001) and effort (p greater than 0.001) at low, comfortable, and high pitch. deltaP[subscript th] was significantly greater in participants with vocal attrition than in normal controls (p greater than 0.001). Nasal breathing reduced P[subscript th] for all controls but not for all participants reporting vocal attrition. deltaP[subscript th] was significantly and linearly correlated with deltaEffort (r[subscript vocal attrition] = 0.81, p greater than 0.001; r[subscript control] = 0.84, p greater than 0.001). We speculate that the greater increases in P[subscript th] in participants reporting vocal attrition may result from delayed or inadequate compensatory response to superficial laryngeal dehydration. Obligatory oral breathing may place voice users at risk for exacerbating vocal attrition. That sol layer depletion by obligatory oral breathing increased P[subscript th] and vocal effort provides support for the role of superficial hydration in maintaining ease of phonation.