Acid trehalase gene (ATH1) expression was decreased using the antisense-RNA technique in Saccharomyces cerevisiae. The 500 bp DNA fragments containing anti-ATH1 gene between +1 and +500 were amplified using PCR and fused to yeast ADH1, CYC1 and ATH1 promoters. Yeast cells harboring the recombinant plasmids had a low activity of acid trehalase and promoted ethanol fermentation compared to the control yeast cells harboring the vector plasmid only. The recombinant yeast had a high viability with 8% (v/v) ethanol.