Crown and root rot of tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici was first detected in Turkey in 1998. Since then, it has become a common disease in commercial greenhouses in the south and south-western part of Turkey. In order to assess the incidence of the disease and obtain isolates of the pathogen for further studies, a survey was conducted in the greenhouses of two major tomato growing provinces, namely Antalya and Mugla in May of 2008. Diseased plant samples were collected from greenhouses where the crown and root rot had been suspected to occur and symptomatic plants were counted. Fifty-three Fusarium oxysporum isolates were obtained from forty-one tomato greenhouses and twenty-eight of them were selected to use in pathogenicity test. For the pathogenicity tests two tomato cultivars 'Newton F-1' and 'Kardelen F-1' commonly found in commercial greenhouses where the disease symptoms existed, were inoculated by root-deep technique with conidial suspension of those isolates. Based upon their pathogenicity reaction eighteen isolates were identified as F. oxysporum f. sp. radicis-lycopersici. The presence of the pathogen was also confirmed by re-isolations from infected tomato plants on selective media for Fusarium spp. As a result, the incidence of the disease was determined as 26.1 and 85.1% in commercial tomato greenhouses from where the pathogen could be isolated and identified, in Antalya and Mugla, respectively.