Paraquat and juglone generate reactive oxygen species (ROS) and are widely used to investigate defense mechanisms against ROS in model animals. We cloned cDNA encoding hsp70 from the rotifer Asplanchna brightwelli. The full-length cDNA was 2134 bp and had an open reading frame of 1929 bp encoding 642 amino acids. The deduced amino acid sequence indicated that the Asphsp70 was a cytoplasmic protein and has the highest similarity 87% with Mus musculus, 86% identity with orthologs of Danio rerio, 84% with Apis mellifera and 81% with Xenopus laevis. Expression of Asphsp70 was analyzed under 1.25, 2.5, 5 and 10 mg/L paraquat and 6.25, 12.5, 25 and 50 μg/L juglone. With paraquat, mRNA expression of Asphsp70 significantly increased immediately after exposure for 1 h (P < 0.05). Expression of Asphsp70 temporarily increased after exposure to 2.5 mg/L for 3 and 6 h, and after 10 mg/L for 3 h (P < 0.05). With exposure to 6.25 μg/L juglone, mRNA for Asphsp70 significantly increased at 1, 3 and 12 h; with 12.5, 25 and 50 μg/L, mRNA expression of Asphsp70 significantly increased immediately for 1 h (P < 0.05). These results indicated that the Asphsp70 gene was important in the response to oxidative stress.