Abstract: In this study, during the B. cinerea tomato interaction the regulation of Sl-WRKY1 which encoding a putative member of the WRKY DNA-binding protein family and act as transcriptional activators co-regulated with PR-proteins expression was investigated in resistance and susceptible tomato cultivars. The studies were performed at the structural level (DNA level) and functional level (RNA level). Results showed that, in spite of the tested tomato cultivars varied in their resistance to grey mould disease, the gene encoding Sl-WRKY1 was existed at DNA level. At RNA level, an induction of Sl-WRKY1 expression was detected in resistant and susceptible cultivars after inoculation with B. cinerea, as compared to the healthy controls. These results indicated that, Sl-WRKY1 gene was related to the defense mechanisms against grey mould disease in tomato. The expression of Sl-WRKY1 gene in the resistant cultivar occurred earlier and stronger while being induced later in the susceptible cultivar. The phylogenatic analysis of 30 WRKY amino acid sequences in different 11 plant species, was constructed. Results showed that, some WRKY genes of S. lycopersicum are phytogenaticaly closed to WRKY genes of A. thaliana, O. sativa, N. tabacum and S. tuberosum.