Asthma and allergies are characterized by variable and subjective symptoms influenced by many genes, molecular mechanisms and environmental factors. The presence of inflammation and oxidative stress in the airways are important biochemical features of asthma and respiratory allergies. Glutathione S‐transferase enzymes (GSTs) play an important role in cellular protection against inflammation and functional genetic polymorphisms in GST genes showed a significant association with asthma and allergy risk. Specifically, our previous study on asthmatic children highlighted GSTA1 and GSTO2 as novel susceptibility loci for asthma. In this study we focused our attention on GSTA1*‐69C/T (rs3957357) and GSTO2*N142D (rs156697) polymorphisms to confirm our previous results in an independent adult study population and to clarify whether GSTA1 and GSTO2 gene polymorphisms are involved in a non‐discriminative pathway towards asthma and respiratory allergy. To accomplish this, we recruited 103 patients with respiratory allergies, 199 patients with asthma, and 200 healthy controls. Genomic DNA extracted from buccal cells was screened for GSTA1*‐69C/T and GSTO2*N142D single nucleotide polymorphisms. The GSTA1*‐69T and GSTO2*D142 variants are both associated with the significant increased risk of asthma, whereas only GSTA1*‐69C/T is significantly associated with allergies. These outcomes confirmed the involvement of GSTO2 loci in asthma, and they suggested that GSTA1 is a common risk factor for asthma and allergies. This article is protected by copyright. All rights reserved.