OBJECTIVES: Intravenous immunoglobulin (IVIG )has demonstrated improvement in chronic inflammatory demyelinating polyneuropathy (CIDP) patients in placebo contolled trials.  However, IVIG is also much more expensive than alternative treatments such as corticosteroids. The objective of the paper is to evaluate, from a Canadian perspective, the cost-effectiveness of  IVIG compared to corticosteroid treatment of CIDP. METHODS: A markov model was used to evaluate the expected costs and QALYs for over 5 years for two treatments for CIDP 1) IVIG, and 2)  corticosteroids.  Patients in the IVIG treatment arm could respod or not respond respond or not respond to treatment in the initial 12 weem model cycle. Patients could relapse or continue to respond wto treatment in subsequent cycles. Based on pooled efficacy data the initial reponse probability for IVIG used in the model was 0.47(95% C.I. 0.36, 0.58).  Based on a published study, the 12 week proability of relaspe used in the model was 0.06 (95% C.I. 0.02,0.14). Non-responding IVIG patients were assumed to be switched to corticosteroids. Patients on corticosteroids were at risk of a number of adverse events (fracture, diabetes, glaucoma, cataract, serious infection) each cycle. RESULTS: Over the 5 year time horizon the model estimated the incrmetnal costs and QALYs of  IVIG treatment compared to corticosteroid treatment to be $105,356 and 0.188 repsectively. The incremental cost per QALY of IVIG was estaimated to be $551,031. The cost per QALY of IVIG was very sensitive to the assumption on frequency and dosing of maintenance IVIG treatment. CONCLUSIONS: Based on common willingness to pay thresholds, IVIG might not be perceived as a cost effective treatment for CIDP.