Six modified endosperm opaque-2 corn varieties from CIMMYT were evaluated at Lajas and Isabela, Puerto Rico in 1983. Two Puerto Rican varieites, Mayorbela and Diente de Caballo, were used as checks. Opaque-2 (o2) corn normally has soft endospoerms, while modified varieties approach the appearance of normal corn. The subplors of each variety were a check, benomyl treatment, and Fusarium moniliforme silk inoculation. Traits measured included incidence of seedborne fungi, plant and ear heights, visual ear infection, ear lengths and diameter, yield and 500 kernel weight, and modification. Yields and modification of the CIMMYT varieties were similar to that of the traditional (non o2) varieties. F. moniliforme was found to be the most important seedborne fungus. The inoculation technique was found to increase incidence of F. monoliforme and should be useful for evaluating large numbers of families in a selection program. Improvement of yield and adaptability of CIMMYT's materials is needed for viable commercial production of these varieties. On the basis of this evaluation, S1 recurrent selection has begun in two modified o2 varieties.