This study was conducted to determine the prevalence of Beet necrotic yellow vein virus (BNYVV) causal agent of rhizomania, in sugar beet cultivation areas in the Lakes District of Turkey, in 2006-2007. During surveys BNYVV suspected leaf, root, and soil samples were collected. Total of 203 soil samples were collected from different locations in the region. Sugar beet cultivar Kasandra plants were grown in these soil samples using bait plant techniques. In order to detect the structures of the vector protozoa Polymyxa betae Keskin in the root tissue of the bait plants, roots were stained with lactofuchsin and examined for the fungal cystosori under a light microscope. Presence of BNYVV was investigated using Double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA). ELISA test results showed that 85 samples were infected with BNYVV (41.87%). ELISA-positive samples for BNYVV were used in the mechanical inoculation studies. Test plants produced typical BNYVV symptoms. Fifty ELISA negative samples when tested by reverse transcription polymerase chain reaction (RT-PCR), BNYVV could be detected in 50% of these samples. The present study provides evidence for occurrence of BNYVV in a major beet growing area in Turkey based on biological, serological and molecular detection of the virus. RT-PCR method was found more suitable and sensitive than DAS-ELISA for the detection of BNYVV.