The establishment of a quantitative determination method by HPLC for adenosine and 3'-deoxyadenosine in Cordyceps militaris is reported. The sample was extracted with water under ultrasonic management for 2 hours. Chromatographic conditions: YWG C18 10 microns 5 mm x 200 mm; mobile phase consisted of NaH2PO4-NaOH buffer solution (pH 6.8); UV detection at 260 nm. The recoveries of adenosine and 3'-deoxyadenosine were 95.8% +/- 0.64% and 100.6% +/- 0.65% (n = 5) respectively.