OBJECTIVE: To review clinical evidence on the efficacy of saline nasal irrigation for treatment of sinonasal conditions and to explore its potential benefits. QUALITY OF EVIDENCE: Clinical trials, reviews, and treatment guidelines discussing nasal irrigation were obtained through a MEDLINE search from January 1980 to December 2001. Most trials were small and some were not controlled; evidence, therefore, is level II, or fair. MAIN MESSAGE: Flushing the nasal cavity with saline solution promotes mucociliary clearance by moisturizing the nasal cavity and by removing encrusted material. The procedure has been used safely for both adults and children, and has no documented serious adverse effects. Patients treated with nasal irrigation rely less on other medications and make fewer visits to physicians. Treatment guidelines in both Canada and the United States now advocate use of nasal irrigation for all causes of rhinosinusitis and for postoperative cleaning of the nasal cavity. CONCLUSION: Nasal irrigation is a simple, inexpensive treatment that relieves the symptoms of a variety of sinus and nasal conditions, reduces use of medical resources, and could help minimize antibiotic resistance.