This study was carried out to identification of Vegetative Compatibility Groups (VCGs) and pathogenicity of Verticillium dahliae isolates obtained from tomato plants in Iğdır province. As a result of survey studies conducted in 18 different regions, 14 isolates were obtained from 629 diseased tomato plants. In the complementation test, the seven isolates were found as VCG2A and VCG2B by using international reference isolates. VCGs of other isolates were not identified. Assessment of the aggressiveness of the KRS-2, YC-13, YY-14, and MLK3-4 isolates was evaluated on tomato (cv. Super). The disease severity was between 15-45% and MLK3-4 isolate had the highest disease severity (45%). Additionally, the effect of temperature on the growth of V. dahliae isolates (TSD-1, MLK3-4 and YY-14) was determined. The isolates showed optimal growth temperatures ranging from 20 to 25 °C (except for TSD-1). In control of fungal diseases, it is very important to describe the disease and pathogen. Therefore, the results of the study are important for tomato growers and researchers.