The prevalence of GSTM1 null genotype with smoking habit was found higher i.e. 57.9% of COPD individuals compared to 31.4% in Control and was found statistically significant with a fourfold risk among the individuals with a combination of GSTM1 null genotype and smoking habit (p<0. This evidence concerns the gene GSTM1 and chronic obstructive pulmonary disease.