Biodiversity of arthropods in Cnaphalocrocis medinalis (Lepidoptera: Crambidae) resistant GM rice (CryIAc1) and non-GM rice fields. Sampling was conducted 15 times using sweeping net and electric aspirator. Biodiversity was analyzed with species richness and Shannon diversity index (H’). Total 28,275 arthropod individuals (12,413 in GM rice and 15,862 individuals in non-GM rice) were collected and there were 22 families, 34 genera and 36 species belonging to 8 orders. There were 19 families, 29 genera, 31 species in GM rice and 20 families 32 genera 34 species in non-GM rice fields. There was no significant difference in species richness and species diversity (H’) between GM and non-GM rice. Species diversity was significantly higher in non GM rice in the insect pest group only in middle and late of August .