Introduction Origanum belonging to the Lamiaceae family is one the most wide-spread genus in the spontaneous fl ora of many landscapes. It has a precious natural resource, as they provide raw material for pharmaceutical industry, modern and traditional forms of medicine and generate employment and income in addition to conservation of biodiversity [1]. The genus includes 43 species of perennial and annual plants, which grow on rocky slopes, at a wide range of altitudes [1, 2, 3]. The aerial part of the plant is often used directly while the extracted essential oils exhibit antimicrobial properties, cytotoxic and antioxidant activities [5]. Taxonomic studies based on morphological characters [3] and on the results of biochemical analysis of the essential oils and their constituent compounds [5] indicate a high degree of variability across species of the Origanum genus. In light of these results, we considered signifi cant to analyze the genetic polymorphism in two species of the Origanum genus - Origanum vulgare L. and Origanum laevigatum Boiss., collected from a region of spontaneous fl ora in Moldova (Orheiul-Vechi). Material and methods The plant material was used in the form of dry leaves. Total genomic DNA was isolated from fully developed leaves using the CTAB extraction protocol [4], by gradually increasing the liquid nitrogen concentration. A total of 8 single decamer random oligonucleotide primers of arbitrary sequence (OPA2, OPA9, OPA19, OPB01, OPG05, OPK17 şi Oligo391) were tested for PCR amplifi cation. DNA amplifi cation according to a basic PCR protocol was performed in a total volume of 15 μL, containing 50 ng of template DNA, 0,4 - 0,6 μM of single primer, 1 U Taq DNA polymerase 200 μM of each dNTP, 2,5 mM MgCl2 [6]. Results and discussions The RAPD-PCR analysis of the Origanum sp. genotypes indicated a high heterogeneity of the results by genotype and tested primers. Based on the electrophoretic spectrum, 82 amplifi cation products were identifi ed with an average of 11,71 bands per primer. The number of amplifi ed fragments varied in the range from 0 to 12 depending on the primer used. The comparative analysis of molecular polymorphism across the named species revealed that the RAPD-PCR generated 47 bands for Origanum vulgare L. and 35 for Origanum laevigatum Boiss. 23 of them are polymorphic and 35 – monomorphic fragments, 22 for O. vulgare L., respectively 13 fragments for O. laevigatum Boiss. The Oligo391 decamer presented six bands for both species, all monomorphic. The obtained results allowed concluding that the most informative primers are: for O. vulgare L. - UBC250 and for O. laevigatum Boiss. - OPK17 showing a maximum number of fragments (12, respectively 9 bands). OPG5 (O. vulgare L.) and UBC250 (O. laevigatum Boiss.) decamers did not generate any amplicons. The most specifi c bands were revealed in the case of OPA02 (O. laevigatum Boiss. - 4) and UBC250 (O. vulgare L. - 12) decamers. Conclusions RAPD-PCR analysis has established a high heterogeneity between Origanum vulgare L. and Origanum laevigatum Boiss. Specifi c particularities of each species depend by tested primers. The most primers showed a high degree of molecular polimorfi sm. The most informative primers are UBC250 for O. vulgare L. and OPK17 for O. laevigatum Boiss.). These studies are the part of Moldova-Romanian project “Genetic intraspecifi c polymorfysm analysis for the elaboration of molecular markers of some medicinal and aromatic plants chemotypes”.