Abstract: The effects of shark protein crude extract administration on liver mitochondrial antioxidant defenses were investigated in rats.Rats were given two consecutive intraperitoneal injections of(thioace-)tamide(TAA,400 mg/kg body weight) and shark protein extract(80 mg/kg body weight) 1 h before TAA treatment with a 24 h interval in model and therapy groups respectively.TAA administration(decreased) the ADP stimulated oxygen consumption,respiratory control ratio(RCR),the P/O value and oxidative phosphorylation ratio in isolated mitochondria,but shark protein extract could suppressed the(effect) of TAA.TAA administration decreased the levels of(glutathione,) glutathione peroxidase,(glutathione) reductase in mitochondria,and shark protein extract administration increased the levels of(glutathione) peroxidase and superoxide dismutase.These illustrated that shark protein extract could (partially) repair mitochondrial respiratory function impaired by TAA administration,and increase(mitochondrial)(antioxidant) defenses.