Objective: To determine the cost effectiveness and cost utility of acetylcysteine versus dimethyl sulfoxide (DMSO) for patients with reflex sympathetic dystrophy (RSD), from a societal viewpoint. Design: An economic evaluation was conducted alongside a double-dummy, double-blind, randomised, controlled trial. Patients were followed for 1 year. The primary outcome measure was the Impairment-level Sum Score (ISS). Utilities were determined by the EuroQOL instrument (EQ-5D). Both cost-effectiveness and cost-utility analyses were performed. Differences in mean direct, indirect and total costs were estimated. Corresponding 95% confidence intervals were calculated by bootstrapping techniques. Results: Both groups (DMSO, n = 64; acetylcysteine, n = 67) showed relevant improvement; no differences in effects were found. Only the total direct costs were significantly lower in the DMSO group for the period of 0-52 weeks. The incremental cost-effectiveness ratios showed that, in general, DMSO generated fewer costs and more effects compared with acetylcysteine. Post-hoc subgroup analyses on cost effectiveness suggested that patients with warm RSD could be best treated with DMSO and patients with cold RSD with acetylcysteine. These results were based on small subsamples. Conclusion: In general, DMSO is the preferred treatment for patients with RSD.