Tobacco streak virus (TSV) belonging to the genus Ilarvirus, family Bromoviridae has isometric particles, positive sense singlestranded RNA genome consisting of three linear segments. TSV can be transmitted mechanically, by plant extract, and seed, although transmission by thrips and pollen has been reported too. TSV has a broad host range and Amaranthaceae, Apocynaceae, Asparagaceae, Brassicaceae, Cruciferaceae, Cucurbitaceae, Graminea, Fabaceae, Rosaceae, Malvaceae and Solanaceae families were reported as host of virus. These properties introduce TSV one of the most important destructive viruse in crop production. First, TSV was reported from soybean (Glycine max) in the Golestan province, then, tobacco (Nicotiana tabacum), sunflower (Helianthus annuus), mungbean (Vigna radiata), potato (Solanum tuberosum), chilli (Capsicum annuum), dahlia (Dahlia pinnata), common bean (Phaseolus vulgaris) and groundnut (Arachis hypogaea) were reported as the host of virus. During 2016 and 2017 years, symptoms of leaf distortion, scorch, mosaic, yellowing and stunting were broadly observed in some lettuce fields. By ELISA test (Double Antibody Sandwich ELISA) and using specific polyclonal antibody, TSV severe infection was confirmed in lettuce field. To confirm ELISA results, total RNA was extracted by RNase Plant Mini Kit (Qiagen, Germany) and used as template for reverse transcription (RT). The production of complementary DNA was carried out using the Mmulv enzyme, and polymerase chain reaction was done by specific primer pairs to amplification a partial of coat protein gene region. The expected fragment with 672 bp was detected and replicated in the RT-PCR reaction. This is the first report of Tobacco streak virus in lettuce fields in Golestan province.