Bisphenol A (BPA), a representative endocrine disrupting chemicals, has adverse effects on growth, development and reproduction in aquatic organisms. The object of this study was to investigate the modulation of antioxidant enzyme - coding genes using quantitative real time RT - PCR (qRT - PCR), enzyme activity and total protein content, to understand oxidative stress responses after exposure to BPA for 48 h in brackish water flea Diaphanosoma celebensis. The BPA (3 mg L-1) significantly upregulated the expression of Cu / Zn - SOD, Mn-SOD, and catalase (CAT ) mRNA. Three GST isoforms (GST-kappa, GST-mu, and GST-theta) mRNA levels significantly increased at the rate of 0.12 mg L-1 of BPA. In particular, GST-mu showed the highest expression level, indicating its key role in antioxidant response to BPA. SOD activity was induced with a concentration - dependent manner, and total protein contents was reduced. These findings indicate that BPA can induce oxidative stress in this species, and these antioxidants may be involved in cellular protection against BPA exposure. This study will provide a better understanding of molecular mode of action of BPA toxicity in aquatic organisms.