Stem rot diseases of tomato, caused by Erwinia carotovora subsp. carotovora, is a serious problem in greenhouses in Turkey. Pathogen causes wilting of the whole tomato plants, water-soaking areas on stem, browning of vascular tissue, hollowing of pith, and soft rotting stem and fruits. The symptom development starts from root or crown region of seedlings in greenhouses. The primary inoculums of the disease on tomato need to be studied to develop effective control strategies in tomato growing areas. In the study, transmission of E. carotovora subsp. carotovora by tomato seeds was investigated. The pathogen isolated tomato seeds, obtained from naturally diseased fruits. Additionally, when tomato seeds artificially inoculated by E. carotovora subsp. carotovora were grown in sterile soil under mist, the germinated seedlings had leaf lesions, irregular black-brown spots and no halo. The diseases incidence was 12%. Our results showed that the disease could be seed-borne. Effect of some physical and chemical seed treatments on E. carotovora subsp. carotovora was investigated in vitro studies. These treatments were found as effective between 40 and 100 ratios. It was evaluated that surface sterilization of the seed with sodium hypochlorite (1% for 3 minutes). The treatment also indicated that E. carotovora subsp. carotovora located on surface of the seed.