In order to maintain the sustainability of greenhouses in Tahtah Dam preservation area, the possibility of using closed substrate culture was investigated. A project with 8 growers started in 2001 after demonstration and training studies carried out between 2000 and 2001 in the area. Under the supervision of the staff of Ministry of Agriculture and Rural Affairs in Menderes District, these growers developed their own systems and produced cucumbers during spring-summer seasons. Besides cucumber production, some growers produced tomato, lettuce or onion during autumn-winter seasons. The same substrate was used without replacing for three successive years. In this study, economic analyses of soilless vegetable production between 2001 and 2004 were performed. After 3 years, two growers, who had 8.63 and 4.93 US $ total net return per m(2) for 3 years, decided to continue with soilless culture technique.