When 'Cavendish' and 'Cocos' banana plantlets derived from tissue culture were inoculated with race 1 or 4 of Fusarium oxysporum Schlecht. f. sp. cubense (E.F. Smith) Snyder & Hansen by immersing roots in a spore suspension for 1 min. susceptible plantlets showed external symptoms of leaf yellowing within two weeks and wilted within four weeks of inoculation. Results of pathogenicity tests with banana plantlets agree with those with mature banana plants which take an average of nine months for expression of external symptoms. Such rapid and simple pathogenicity tests should be useful for race determination of F. oxysporum f. sp. cubense.