In a prospective, randomized, controlled, double-blind trial we compared the effectiveness of endonasal irrigations with Ems salt solution to that with sodium chloride solution in the treatment of adult patients with chronic paranasal sinus disease. Subjects (n = 40) were randomly allocated to treatment either with isotonic Ems salt solution or with isotonic sodium chloride solution. The treatment consisted of endonasal irrigation twice daily and additional nasal spray as required. Nasal endoscopy, plain radiography of the paranasal sinuses, olfactometry, anterior rhinomanometry, and a saccharin-clearance test were carried out on days 1 and 7. Patients recorded rating scales of general discomfort, nasal airway obstruction, agreeableness of the irrigation, duration of improved nasal resistance after each irrigation, and the amount of additional nasal spray in a diary. Nasal air flow was not improved significantly. Subjective complaints, endonasal endoscopy, and radiography results revealed a significant improvement in both groups (P = 0.0001). In comparison, the two groups were not significantly different in outcome. Endonasal irrigations with salt solutions are effective in the treatment of chronic sinusitis, and a significant difference between Ems salt and sodium chloride was not observed.