Although propylene-and-polyethylene-glycol and saline have been used in clinical studies as placebos, their possible therapeutic role as wetting agents in the treatment of perennial rhinitis was investigated. Clinical and laboratory response to these agents was measured in eighteen patients during a 2-week baseline period and with 4 weeks of active treatment in a double blind randomized study. After 2 and 4 weeks there was a significant improvement compared to baseline in nasal function (P less than 0.05) and blockage index (P less than 0.01) combining both groups, with no difference between treatments. Patients had less sneezing at 2 and 4 weeks (P less than 0.01), and less stuffiness at 4 weeks (P less than 0.01). There was a significant correlation between improvement in blockage index and nasal biopsies when both were judged independently of the other. This study has demonstrated that wetting agents offer both subjective and objective improvement in the treatment of perennial rhinitis and merit consideration prior to (or along with) other agents with known systemic side effects.