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The demand for decaffeinated coffee is increasing because the stimulatory effects of caffeine can adversely affect sensitive individuals by triggering palpitations, increased blood pressure and insomnia. Three N-methyltransferase enzymes are involved in caffeine biosynthesis in coffee plants — CaXMT1, CaMXMT1 (theobromine synthase) and CaDXMT1 (caffeine synthase), which successively add methyl groups to xanthosine in converting it into caffeine^,,. Here we describe the construction of transgenic coffee plants in which expression of the gene encoding theobromine synthase (CaMXMT1) is repressed by RNA interference (RNAi). The caffeine content of these plants is reduced by up to 70%, indicating that it should be feasible to produce coffee beans that are intrinsically deficient in caffeine.