The beneficial effects of a traditional Chinese medicine, Cordyceps sinensis (Cs), on mice with hypoferric anaemia were evaluated by NMR spectroscopy. Experimental hypoferric anaemia was induced in mice by feeding with an Fe-free diet for 6 weeks. They were then given extract from cultured Cs (200 mg/kg body weight daily, orally) and were placed on an Fe-containing recovery diet (35 mg Fe/kg diet) for 4 weeks. In vivo 31P and 2H NMR spectra acquired noninvasively and quantitatively at weekly intervals were used to evaluate hepatic energy metabolism and blood flow in the mice. During the 4-week Cs-extract treatment, consistent increases were observed in liver beta-ATP: inorganic phosphate value by liver 31P NMR spectroscopy, representing the high energy state, and in blood-flow rate as determined by 2H NMR spectroscopy of deuterated water (D2O) uptake after intravenous injection of D2O. The haematological variables (the packed cell volume and the haemoglobin level) and the hepatic intracellular pH, which was determined from the NMR chemical shift difference between the inorganic phosphate peak and the alpha-phosphate peak of ATP, were not significantly different between Cs-extract-treated and control mice. As blood flow and energy metabolism are thought to be linked, the Cs-extract-increased hepatic energy metabolism in the dietary hypoferric anaemic mice was concluded to be due to increased hepatic blood flow.