The objective of this study was to assess the long-term course and treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). We evaluated, according to a predefined protocol, a series of 60 CIDP patients who received a long-term course of steroids and immunosuppressants. Eighteen of them also had monoclonal gammopathy of undetermined significance (MGUS). Mean follow-up was 4.4 years and was similar for CIDP and CIDP-MGUS patients. At the end of the follow-up, improvement was ascertained in 60% of patients (69% CIDP, 39% CIDP-MGUS). Complete remission was achieved in 13%. Out of 26 patients receiving steroids as a monotherapy, 19 improved (73%). The following variables were predictive of a better outcome: female gender, younger age at onset, relapsing-remitting course, and absence of axonal damage at neurophysiologic study. In the multivariate analysis, younger age at onset and demyelination without axonal damage still retained an independent positive value.