The glucose catabolism in several varieties of pepper fruit has been investigated by means of tracer techniques employing glucose-1, -2, -3(4), and -6-C14as the labelled substrates. A method is presented whereby the participation of individual pathways in these fruits may be identified and estimated. It was found that 28–36% (among the varieties tested) of the glucose catabolized was routed through a direct oxidative pathway, the remainder being oxidized via the Embden–Meyerhof–Parnas and tricarboxylic acid cyclic processes. No significant difference in pathway distribution was found between green mature peppers and red mature peppers.