The effects of combined intranasal and systemic glucocorticoid steroids on the local inflammatory response, and symptoms due to experimental rhinovirus infection were studied in 45 adults randomized to prophylaxis with either placebo or steroids. Intranasal beclomethasone (168 micrograms twice a day) was begun 4 days before viral challenge and continued 5 days after challenge. Oral prednisone (30 mg twice daily) was given for 3 days beginning 1 day before challenge. During the first 48 h after viral inoculation, nasal obstruction, nasal mucus weights, and kinin concentrations in nasal lavages were lower in steroid recipients, but subsequent increases in these variables in the steroid group resulted in no significant cumulative differences between treatment groups. These data suggest that steroid prophylaxis may suppress nasal inflammation and cold symptoms during the first 2 days in experimental rhinovirus colds.