Intravenous immunoglobulins (IVIg) and steroids are similarly effective as initial treatments in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) but little is known on their comparative riskbenefit profile over the long period. We compared the efficacy and safety of six-month therapy with IVIg or methylprednisolone (IVMP) in CIDP. Fortysix patients fulfilling EFNS/PNS criteria for definite CIDP were randomly allocated in a 1:1 proportion to receive IVIg (IgVena, Kedrion SpA) (2g/kg) + IVMPplacebo or IVMP (2 g) + IVIg-placebo over four days, monthly for six months. Patients were then followed for six months to assess relapses. The primary endpoint was the difference in the number of patients suspending IVIg or IVMP for intolerance or inefficacy. Secondary end-points included the difference in the improvement in assessment scales after 15 days, 2 months and 6 months of therapy, and the difference in the proportion of patients worsening after therapy discontinuation. Forty-five patients (24 on IVIg and 21 on IVMP) were evaluated. One was excluded for inappropriate inclusion. More patients suspended IVMP (10/21, 52.5%) than IVIg (3/24, 12.5%) (p = 0.0085) for unresponsiveness or intolerance to therapy. At the end of the 6-month therapy, both groups had similarly improved in the Rankin, ONLS, Rotterdam and SF-36 quality of life scales and the IVIg group also in the MRC and sensory scores and time to walk 10 meters. After therapy discontinuation more patients on IVIg (8/21, 38.1%) than IVMP (0/10) worsened and required further therapy. More patients on IVMP than on IVIg suspended therapy during the six months of therapy because of inefficacy or adverse events. After therapy discontinuation, more patients treated with IVIg than with IVMP worsened and had to resume therapy.