This study combined the micro-cross-section cultural system with in vitro mutagenesis induced by ethyl methanesulphonate (EMS) to screen for fusarium wilt-resistant lines of Brazil banana (Musa spp., AAA). The results indicated that the optimum EMS concentration and duration for the treatment of micro-cross-sections cut from the pseudostem of tissue-cultured plantlet were 300 mm and 60 min, respectively. Under the optimal treatment, an average of 2·2 regenerated shoots were produced from each explant. One hundred regenerated plantlets were used for screening for fusarium wilt-resistant lines by the early screening technique. The initial disease symptom – yellowing in lower leaves of susceptible plantlets – was observed 2 weeks after inoculation. After 2 months, only six plants survived – the putative fusarium wilt-resistant lines. The fusarium wilt pathogen Fusarium oxysporum f. sp. cubense race 4, was identified in the preliminary test field by a SCAR marker technique. Of the six putative resistant lines, five survived the preliminary field test. The regenerated plantlets from these five fusarium wilt-resistant lines were subjected to early screening again, where they showed markedly reduced disease incidences compared with regenerated plantlets of Brazil banana (control). It was concluded that EMS-induced mutation of banana through the micro-cross-section cultural system is potentially useful for banana improvement.