The productivity of ethanol fermentation processes, predominantly based on batch operation in the U.S. fuel ethanol industry, could be improved by adoption of continuous processing technology. In this study, a conventional yeast fermentation was coupled to a flat-plate membrane pervaporation unit to recover continuously an enriched ethanol stream from the fermentation broth. The process employed a concentrated dextrose feed stream controlled by the flow rate of permeate from the pervaporation unit via liquid-level control in the fermenter. The pervaporation module contained 0.1 m(2) commercially available polydimethylsiloxane membrane and consistently produced a permeate of 20%-23% (w/w) ethanol while maintaining a level of 4%-6% ethanol in a stirred-tank fermenter. The system exhibited excellent operational stability. During continuous operation with cell densities of 15-23 g/l, ethanol productivities of 4.9-7.8 gl(-1) h(-1) were achieved utilizing feed streams of 269-619 g/l glucose. Pervaporation flux and ethanol selectivities were 0.31-0.79 lm(-2) h(-1) and 1.8-6.5 respectively.