Gout is a common condition which is mainly treated with the hypo-uricemic agent, allopurinol. Although allopurinol is generally a well-tolerated drug, there is a small risk of developing potentially fatal complications, such as allopurinol hypersensitivity syndrome. Recent advances in pharmacogenomics have made possible the identification of genes which confer susceptibility to specific drugs. A recent multi-national case-control study has reported allopurinol as the most common drug associated with Stevens-Johnson syndrome and toxic epidermal necrolysis. Several studies have established a strong association between the human leukocyte antigen (HLA)-B*5801 gene and development of Stevens-Johnson syndrome and toxic epidermal necrolysis. The allele frequency of HLA-B*5801 is highest in the South East Asian population.Since other hypo-uricemic agents are available, patients may wish to have HLA-B*5801 testing before being started on allopurinol. As the test for HLA-B*5801 is expensive, time-consuming and only available in selected laboratories, there is a need to evaluate the utility and cost-effectiveness of this test in our region.