To assess the efficacy of corticosteroids in acute vestibular vertigo, we randomly selected 20 patients so that half took methylprednisolone and half took placebo. Extensive neurotologic examination confirmed the diagnosis. If no significant reduction of vertigo occurred within the first 24 hours of treatment, patients were instructed to switch medications. Patients were followed up prospectively for 1 month. Of the 10 patients receiving methylprednisolone, 9 had a marked reduction of vertiginous symptoms and 1 switched to the placebo medication. Of the 10 patients receiving placebo, 3 had relief of vertiginous symptoms, while the 7 with persistent symptoms switched to methylprednisolone and had subsequent effective reduction of vertigo within 24 hours. The electronystagmogram returned to normal within 1 month in all 16 patients taking methylprednisolone, but remained abnormal in 2 of the 4 patients treated with placebo. One patient receiving methylprednisolone had a relapse of symptoms when the dosage was tapered, but symptoms again remitted when the dosage was increased to 32 mg/d. From this double-blind, prospective, placebo-controlled, crossover study, we conclude that methylprednisolone is much more effective than placebo in reducing vertiginous symptoms in patients with acute vestibular vertigo.