The study was carried out in the field and greenhouse of tomato growing areas in Samsun province, aim of the study was determinate, disease of tomato plants root and crown rot. As a result of survey study 773 fungal isolates was obtained from diseased tomato plants 2005-2006. Percentages of the 286 fungi were isolated an follows in 2005, 87.1% Fusarium spp., 6.6% other fungi, 3.8% Rhizoctonia spp. and 2.4% Pythium spp., total 487 fungi were isolated as follows 91.8% Fusarium spp., 3.9% Rhizoctonia spp., 3.7% other fungi, 0.6% Pythium spp. Identification study of based on widespread species that 47.9%, F. oxysporum, 3.8%, Rhizoctonia were the most widespread species in all fungi. P. ultimum was only 0.3% ratio in 2005. Among Fusarium and Rhizoctonia species F. oxysporum (52.4%) and Rhizoctonia solani (3.1%) were the most widespread species in all fungi in 2006. Among Pythium species P. ultimum and Pythium HG-grup were equal amount as 0.3% ratio. As result of pathogenicity test among Fusarium isolates the highest virulence were belong to F. oxysporum isolates some of these isolates were wilt diseases agent F. oxysporum f. sp. lycopersici and some were root and crown rot disease agent F. oxysporum f. sp. radicis lycopersici that caused differential symptoms from the each other. In Pythium species obtained that P. ultimum's isolates were more highly virulent than the others. Other Fusarium spp., Pythium spp. and Rhizoctonia spp. isolates virulence were had different ratio according to our research result.