The rDNA intergenic spacer (IGS) structure of Cannabis sativa contains six variable repeat motifs within a locus spanning 1387 base pairs. The degree of variation of the first three motifs was examined using 77 samples from cannabis samples. The samples originated from five seizures in Taiwan and seed stocks from six different countries. The results showed that there were four types of sequences producing PCR products at either 255, 260, 264 or 265 base pairs. The data obtained indicates that this region of rDNA IGS exhibits a degree of polymorphism that while insufficient by itself can be added to a multiplex with other cannabis STR loci.