Field and greenhouse evaluations of commercial varieties of Upland and Pima cotton have been conducted in the San Joaquin Valley of California to expose a range of commercial varieties to Race 4 Fusarium oxysporum vas infectum.  These entries were evaluated for survival percentages, foliar symptoms, root vascular symptoms, and some measures of plant vigor (node counts and plant height).  Field evaluations were done in fields confirmed as having both presence fo the Race 4 FOV Fusarium pathogen and observations of significant symptoms and mortality issues with cotton grown in the field during the prior year.  Greenhouse trials were done in potting mix utilizing plants inoculated with Fusarium Race 4 using a root-dip technique during the seedling stage.   A wide range of levels of sensitivity to Race 4 Fusarium were identified in these trials, and information regarding basic levels of responses will be presented.