The Southern Green Stink Bug, Nezara viridula (L.) (Heteroptera: Pentatomidae), is a cosmopolitan and economically important pest to several crops. Studies on N. viridula migration and population structure have been neglected. We studied geographically distinct Brazilian N. viridula populations to assess their variability and to determine gene flow among them. DNA from specimens collected on soybean fields were subjected to RAPD analysis to determine genetic similarity and population structure parameters. All N. viridula populations studied were genetically distinct from the others. The maximum similarity occurred between populations from Londrina and Sertanópolis (Parana State). The Cruz Alta population was the most divergent from the others. Despite the short distance between Cambé and Londrina (ca. 29 km), and the absence of geographic barriers, both populations clustered in different groups and the estimated gene flow index (Nm) among them was 2.02, indicating relatively restricted migration. The estimated overall index, Nm was 1.41 suggesting that N. viridula is a better flier than the Neotropical Brown stink bug, Euschistus heros (Nm =0.83).