Simultaneous saccharification and fermentation (SSF) of alkaline hydrogen peroxide pretreated Antigonum leptopus (Linn) leaves to ethanol was optimized using cellulase from Trichoderma reesei QM-9414 (Celluclast(R) from Novo) and Saccharomyces cerevisiae NRRL-Y-132 cells. Contrary to the saccharification optima (2.5% wlv substrate concentration, 50 degrees C, 4.5 pH, 40 FPU cellulase g(-1) substrate and 24h reaction time), the SSF optima was found to be somewhat different (10% wlv substrate, 40 degrees C, 100 FPU cellulase g(-1) substrate and 72h). Better ethanol yields were obtained with SSF compared with the traditional saccharification and subsequent fermentation (S&F) and when the cellulase was supplemented with beta-glucosidase.