A randomized placebo-controlled study has demonstrated no effect of prednisolone in customary dosage on idiopathic sudden sensorineural hearing loss (ISSNHL). The aim of the present paper is to analyse a larger patient group by meta-analysis of data from the RCT together with a corresponding material drawn from the Swedish national database for ISSNHL. Data from 192 patients, 18-80 years with ISSNHL, were available. All had an acute hearing loss of at least 30 dB measured as PTA in the three most affected contiguous frequencies. All patients had been enrolled within one week after onset and evaluated by audiograms after 3 months. 45/99 (RCT) and 54/99 (the database) had been treated with prednisolone in tapering doses from 60 mg daily and 42/93 with placebo (RCT) or 51/93 with no treatment (the database). Primary outcome was the mean hearing improvement on day 90 for the different groups. A mean difference of greater than 10 dB improvement was required to demonstrate a treatment effect for prednisolone compared to placebo/no treatment. No significant difference was seen between the prednisolone group and placebo/no treatment (p = 0.06). Total recovery was 38 % in prednisolone group, 40 % in the placebo and 14 % in the no treatment group. Vertigo at the onset of hearing loss and age at onset had an equal negative prognostic value in all groups and signs of inflammation had a positive effect. Prednisolone in customary dosage does not influence recovery after ISSNHL.