Broomrape ( Orobanche cumana Wallr.) is an obligate parasite of higher plants which affects sunflower in many countries cultivating this crop. For the past decades it is noted the formation of new highly virulent biotypes of broomrape and their spreading to other areas. In our work we studied the molecular genetic diversity of broomrape populations of O.cumana parasitizing on sunflower in Russia Romania and Kazakhstan by using codominant microsatellite markers. During cluster analysis the broomrape populations are divided into two clusters regardless of their racial composition. One cluster grouped 19 samples from Russia and Kazakhstan and the other ' 5 populations from Romania. The genetic distance between clusters according to Nei was 0.137. The analysis of molecular variance (AMOVA) revealed that 22% of genetic variability was due to differences among the gene pools and 78% was due to differences within the gene pools. Pairwise comparisons made using Wright's statistics showed that the differences between these two gene pools are sufficient (Fst = 0.219) to state the existence of a small genetic differentiation between them. Descriptive population genetic statistics for each of the two pools showed that the broomrape populations from the former Soviet Union countries are characterized by a higher level of intrapopulation diversity than the populations from Romania. Molecular genetic differences between broomrape populations parasitizing on sunflower on the post-Soviet territory and in Romania were insignificant. Possible reasons for these results are being discussed.