The total cost of antibiotics, rather than acquisition costs alone was estimated. Preparation and administration costs, laboratory and monitoring costs, and labour costs are considered separately for the major antibiotics used within Christchurch Hospital. The oral route of antibiotic administration is by far the cheapest. The cost of infusion therapy compared with an IV push is considerable. This added about +15-+30 in equipment costs and another +20-+30 in labour costs and often constituted over 50% of the total cost of therapy. The cost of adverse reactions and differences in efficacy should ultimately be included but it was impossible to quantitate these factors in terms of absolute costs. Acquisition costs alone are a poor guide to the true costs of therapy. The cost of administering the drug should be considered in the contexts of efficacy, toxicity and impact on the environment. We contend that these considerations should be implied to the overall impact on the hospital budget, rather than the pharmacy costs alone.