A S. cerevisiae strain expressing both arabinose and xylose utilization pathways, and in particular to a S. cerevisiae strain fermenting both arabinose and xylose to ethanol, and more particularly a S. cerevisiae strain with overexpression or upregulation of xylose- or aldose reductase (XR, AR) with xylitol dehydrogenase (XDH) together with overexpression or upregulation of genes forming an arabinose utilization pathway. The invention encompasses both laboratory and industrial strain having these properties.