Introducing large numbers of target genes into the chromosome of Saccharomyces cerevisiae via delta-sequence-mediated integration is a good strategy for exploring the effects of gene dosage on expression and secretion of heterologous proteins. The expression of exogenous genes might be further improved through meiosis in an isogenic triploid. Here, a stable strain A-8 was screened from 35 sexual spore colonies obtained from an isogenic triploid integratively expressing bgl1 from Aspergillus aculeatus. The corresponding beta-glucosidase activity in this strain was increased by similar to 120 % compared with the parent strain BGL-a. Measurement of doubling time, flow cytometry, and mating experiments further confirmed that A-8 was a spore-forming strain obtained from a triploid parent. Thus, combining delta-integration and meiosis in an isogenic triploid is a promising approach for improving the expression of exogenous proteins in S. cerevisiae.