Sunflower, (Helianthus annuus) is considered as an important oilseed crop grown in many countries including Iran. In recent years, Tobacco streak virus (TsV) has been found in sunflower fields in Iran. TsV is a type member of Ilarviruses, and infects a wide range of crops as well as weeds. In this survey and during 2008, two isolates of sunflower and one isolate of faba bean collected from, Iran, India and Sudan respectively were taken for a study where some of the biological and molecular characterization of these isolates were compared. The molecular weights of coat protein of the isolates (employing SDS-PAGE) were estimated as 30.9 kDa. Western blotting confirmed the results. In laboratory inoculation tests, the virus was found to infect some plants. The host range and diversity of symptoms were different in the three isolates. In TAS-ELIA test, no serological diversity observed among the isolates using TsV monoclonal antibody (AP-696 DSMZ). A fragment of 747nt was amplified for each isolate through the specific primer pair of the CP region. Following the cloning and sequencing of the fragments of each isolate, phylogenetic analysis with nucleotide and amino acid sequences of coat protein of these isolates revealed that Iranian and Sudanese isolates being close to each other stood in one group whereas the Indian isolate with 91% similarity belonged to another.