Only a few studies have addressed the cost-effectiveness of pharmacogenetics interventions in healthcare. Lack of health economics data on aspects of pharmacogenetics is perceived as one of the barriers hindering its implementation for improving drug safety. Thus, a recent Institute for Prospective Technological Studies (IPTS) study, entitled 'Pharmacogenetics and pharmacogenomics: state-of-the-art and potential socio-economic impact in the EU' included an explorative cost-effectiveness review for a pharmacogenetic treatment strategy compared with traditional medical practice. The selected case study examined the cost-effectiveness of thiopurine methyltransferase (TMPT) genotyping prior to thiopurine treatment in children with acute lymphoblastic leukemia (ALL). Information for the cost-effectiveness model parameters was collected from literature surveys and interviews with experts from four European countries (Germany, Ireland, the Netherlands and the UK). The model has established that TPMT testing in ALL patients has a favorable cost-effectiveness ratio. This conclusion was based on parameters collected for TPMT genotyping costs, estimates for frequency of TMPT deficiency, rates of thiopurine-mediated myelosuppression in TPMT-deficient individuals, and myelosuppression-related hospitalization costs in each of the four countries studied. The mean calculated cost per life-year gained by TPMT genotyping in ALL patients in the four study countries was euro 2100 (or euro 4800 after 3% discount) based on genotyping costs of euro 150 per patient. Cost per life-year gained is expected to further improve following the introduction of the wider use of TMPT genotyping and the availability of lower cost genotyping methods. Our analysis indicates that TPMT genotyping should be seriously considered as an integral part of healthcare prior to the initiation of therapy with thiopurine drugs.