The contents of six Ephedra alkaloids, namely ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine and methyl-pseudoephedrine, in 12 species of Chinese Ephedra collected in 24 districts were determined by high performance liquid chromatography (HPLC). Zorbax CN column (25 cm x 4.6 mm I.D.) was used and the temperature of column oven was 23-25 degrees C. Dibutylamine phosphate solution 0.0009 mol/L (pH 2.2) was used as the mobile phase at flow rates: 0.8 ml/min for the first 7 minutes, raised to 1.5 ml/min in 30 sec and maintained for 16 minutes. The alkaloids eluted were detected at wave-length 210 nm. The results showed that ephedrine and pseudoephedrine are the main components in these Ephedra herbs, but the contents of the six Ephedra alkaloids vary greatly with the plant species. The contents of total alkaloids are higher and ephedrine is the main component in samples derived from Ephedra sinica, E. equisetina, E. monosperma and E. intermedia var. tibetica; but in E. intermedia and E. lomatolepis, the content of pseudoephedrine is higher than that of ephedrine. Methylephedrine content is higher in E. intermedia var. tibetica produced in Xizang (Tibet) and in E. sinica produced in north-eastern China than that in other species. The results also showed that the samples derived from E. przewalskii and E. lepidosperma contain so little alkaloids (less than 0.1%) that they are considered not suitable to be used as the drug Ma Huang. It is of interest that the cultivated Ephedra sinica showed lower alkaloids content compared with that growing wild.