Fusarium wilt has become an important cotton disease problem in California in view of its rapid spread and potential for causing crop losses. The present study was made to evaluate soil solarization as a possible control for this disease. Field plots with a history of Fusarium wilt at Shafter, CA. were solarized during June and July, 1982. The densities of Fusarium oxysporum f. sp. vasinfectum (F.O.V.) and Meloidogyne incognita (M.i.) in May before solarization were 2608 propagules/gm. soil and 60 larva/250 cc of soil. After solarization, less than one propagule/gm soil of F.O.V. and no larvae of M.i. were detected in soil samples. A control treatment consisting of fallowed soil had 1122 F.O.V. propagules/gm. soil and 8 larvae of M.i./250 cc soil. In 1983, the incidence of Fusarium wilt was 7 percent in the solarized plots and 12 percent in the fallow (non-solarized) treatment. Lint yields for both treatments in 1983 were similar. The incidence of wilt in 1984 had risen to 23 percent in solarized plots and to 61 percent in the fallowed treatment. The populations in 1984 of F.O.V. and M.i., although increasing to 250 propagules/gm. soil and to 15 larvae/250 cc of soil in the solarized treatments, were considerably less than the populations of these pathogens in the fallowed treatment (913 propagules of F.O.V./gm soil and 163 larvae of M.i./250 cc soil. In 1984, cotton lint yields and disease incidence in the solarized and fallowed treatments reflected the rates of increase of populations of the pathogens. The solarization treatment was an effective management practice for Fusarium wilt for at least two growing seasons while the fallow treatment was effective for one season.