OBJECTIVES: To conduct a cost analysis of acamprosate in maintaining abstinence in weaned alcoholic patients in Belgium. METHODS: The analysis was based on a state-transition approach, comparing the use of acamprosate versus ‘doing nothing’ (no pharmaceutical maintenance treatment) in alcoholic patients after a detoxification. The analysis considered the probability of additional relapses, over a period of 24 months. Clinical data with regard to relapse rates were obtained from a controlled double-blind trial by Witworth et al., 1996 (n=448), involving 12 months treatment with acamprosate and 12 months follow-up. This trial showed that the advantage of acamprosate over placebo in preventing relapse continued during the 12 months after cessation of treatment. Treatment patterns and resource utilisation in first line were retrieved from a Belgian survey among 129 GPs. Data on resource utilisation in second line were available from a large open pragmatic prospective Belgian trial (n=582). Costs were calculated from the perspective of health insurance. Unit costs were obtained from official listing and hospital statistics. RESULTS: Net cost savings of 21,301 BEF per patient were obtained over a 24-month period for acamprosate at a daily cost of 78.6 BEF for the health insurance compared to “doing nothing.” Most savings were obtained by avoiding acute hospitalisations for detoxification and institutionalized rehabilitation. Various sensitivity analyses showed a large robustness of the conclusions. A global anticipated net saving of 70 million BEF for the Belgian health care sector over 2 years was estimated. CONCLUSIONS: The results of our analysis show that acamprosate is a cost saving intervention in maintaining abstinence in weaned alcoholic patients, if applied during a period of 12 months after detoxification.