The authors examined 312 outpatients, including 100 with otorrhea, 144 with rhinorrhea and 68 with pharyngeal discharge. The pH of otorrhea was generally acid, except in 2 cases of diffuse otitis externa where the discharge was strongly alkalihe. Otorrhea in purulent otitis media was mucopurulent or purulent and was strongly acid. The pH of rhinorrhea ranged from 6.6 to 7.4, being generally weakly alkaline. In acute rhinitis, it was alkaline in half the cases; a tendency to greater alkalinity showed in cases of marked swelling of the inferior nasal conchae. In chronic paranasal sinusitis, the pH generally shifted to the acid side; in acute paranasal sinusitis and in nasal polyps, it was weakly alkaline in all cases; and in allergic rhinitis it was neutral with in a narrow range. the usual pH of oral and pharyngeal discharges ranged from 6.4 to 7.0, being generally weakly alkaline. The character of inflammatory discharges was serous or mucous in all cases, except for a case of peritonsillar abscess with mucopurulent discharge; the pH was weakly alkaline in 5 cases (7.4 per cent), neutral in 26 (38.2 per cent), and acid in 37 (54.4 per cent). When these discharges changed in character from seromucous to purulent, their pH was lowered.