Abstract. Inter-simple sequence repeat (ISSR) markers were used to examine the level of genetic diversity in mangosteen. Twenty three accessions of the Garcinia mangostana collection from Sumatra region were screened for ISSR markers. Eleven random ISSR primers were chosen to differentiate the investigated accessions. The primers generated 72 bands of which 42 (58%) were polymorphic and 30 bands (42%) monomorphic. From the 11 primers tested, two primers were monomorphic. Seven of the nine polymorphic primers produced fingerprint profiles unique to the RT accession from Tembilahan (Riau Province). Cluster analysis divided the accessions into two major groups with genetic similarity coefficient ranging from 0.44 – 0.96. The first group contained only cultivar RT (elliptical stigma lobe) and the second group consisted of 22 accessions (round stigma lobe) which could be divided clearly into six sub-clusters. One of the sub-clusters contained accessions from the same region of Bangka Island and the others contained combination of accessions derived from different locations. The result shows that mangosteen accessions with different genetic background exist in this region. This confirms the general opinion that mangosteen is uniform in genetic.
Key words: Inter-simple sequence repeat, mangosteen, genetic similarity.