Background Patients with severe eczema frequently receive systemic glucocorticosteroids. The efficacy of prednisolone and other steroids, however, has never been evaluated appropriately. A meta-analysis indicated that ciclosporin is the best evaluated systemic treatment for eczema. Objectives To investigate the comparative efficacy of prednisolone and ciclosporin for severe eczema. Methods In an investigator-initiated double-blind randomized multicentre trial, adults with severe eczema (objective SCORAD ≥ 40 and Dermatology Life Quality Index ≥ 10) were randomly allocated to receive prednisolone (initial dose 0·5-0·8 mg kg^-1 daily) for 2 weeks followed by placebo for 4 weeks or ciclosporin (2·7-4·0 mg kg^-1 daily) for 6 weeks and followed for another 12 weeks. Concomitant treatment included a moderately potent topical steroid, emollients, and continuation of antihistamines. Primary endpoint was the proportion of patients with stable remission, i.e. ≥ 50% SCORAD improvement under active treatment and no flare (≥ 75% of baseline SCORAD) during follow-up. Sample size calculation indicated that 66 patients were needed to see clinically relevant differences between groups. Analysis was by intention-to-treat (ClinicalTrials.gov Identifier: NCT00445081). Results Because of unexpectedly high numbers of withdrawals due to significant exacerbations of eczema (n = 15/38) an independent data monitoring and safety board proposed early study termination. Thirty-eight patients were randomized and analysed. Stable remission was achieved in one of 21 patients receiving prednisolone compared with six of 17 patients treated with ciclosporin (P = 0·031). Conclusions Ciclosporin is significantly more efficacious than prednisolone for severe adult eczema. Despite its frequent use in daily practice, prednisolone is not recommended to induce stable remission of eczema.