In this study, we used direct incubation of watermelon dissected seeds on Komada`s selective medium for Fusarium spp. and incubation of entire seed on the same medium or on 2% agar medium. Identification of fungi was based on morphological criteria and also according to Koch`s postulate. Isolates from dissected seed were identified as F. oxysporum f. sp. niveum and F. solani f. sp. cucurbitae. These fungi were found to be externally and internally seed borne in watermelon. This is the first report of localization of Fusarium spp. transmitted by watermelon seeds in Tunisia.