Agrobacterium rhizogenes harbouring the binary vector pLN35 which carries the antisense ACC oxidase gene from pTOM13 was used to transform ‘Shogun’ broccoli plants. Molecular analysis using polymerase chain reaction (PCR) and Southern blotting confirmed the transgenic nature of these plants. Ethylene production by the mature heads was evaluated in normal and three transgenic antisense plants using a gas chromatograph. The transgenic antisense plants TA3 (8 copies), TA4 (1 copy) and TA5 (8 copies) showed an ethylene production that was reduced by 39%, 42% and 77% respectively. Analysis of these mutants suggested that pTOM13 encodes a polypeptide similar to that involved in conversion of ACC to ethylene in broccoli.