Glutathione S-transferase (GST) enzymes play an important role in drug metabolism. GST is a multigene family of enzymes involved in the detoxification and in a few instances activation of a wide variety of chemicals. Detoxification features make it plausible to search for GST polymorphism in patients with drug eruption. The GSTM (mu), GSTT (theta) and GSTP (pi) have been shown to be polymorphically distributed. The GSTT1, GSTM1 and GSTP1 gene polymorphism were detected using real-time PCR. GSTM1 and GSTT1 null genotypes were found to be associated with an increased risk of drug eruption (OR 2.27, 95% CI 1.20-5.21; OR 2.48, 95% CI 1.12-6.39, respectively). No relationship was observed between the null combination of the GSTM1 and GSTT1 genotype polymorphisms and drug eruption risk (OR 2.65, 95% CI 0.62-11.25). Our results show that GSTP1 polymorphism is not a significant contributor to drug eruption risk. The GSTM1 and GSTT1 gene polymorphisms seem to be associated with the development of drug eruption. Further studies may shed additional light on the role of GSTM1, GSTT1 and GSTP1 in drug eruption.