RESUMEN
<p><b>OBJECTIVE</b>To study rDNA ITS sequence differences between F type and that of H type of Dendrobium officinale in main habitat of China.</p><p><b>METHOD</b>The population differences of the rDNA ITS region (including ITS1, ITS2, 5.8S) sequences of D. officinale were studied by the method of DNA sequences analysis.</p><p><b>RESULT</b>There were two different sites between the rDNA ITS sequence of F type and that of H type. One was in ITS1 region, and the other was in 5.8S region. It was proved that there was some relativity between the character of rDNA ITS region and the life type of the populations. The phenomenon of single nucleotide polymorphism (SNP) existed in 5.8S region of rDNA ITS region between F type and H type. The sequences of rDNA ITS region of D. officinale were reported for the first time, and the sequences of ITS region ranged 634 bp (ITS1 231 bp, ITS2 240 bp, 5.8S 163 bp).</p><p><b>CONCLUSION</b>The analysis of rDNA ITS of D. officinale deeply reveal the population differences of D. officinale of F type and H type.</p>