Enzyme activity of alpha-glucosidase (alpha-G) from worker bees, A. cerana, at different stages was assayed. Emerged bees were marked with painting color and counted as 0 day. Bees at desired ages were collected during 0-29 days with the time interval of 3 days. The sample collection had been performed from February to April 2003. Low activity was obtained from samples of all stages collected in February but not from those collected in March and April. Considering the activity profile from those 3 groups, they are similar. Briefly, the low activity was found in emerged bees. Then, the activity got increased in 18-day and 24-day workers. Older bees show decreasing activity of alpha-G. The optimum condition for a-G activity in the crude extract was at pH 5.0, at temperature of 45 ํC, and at incubation of 30 min. The concentration of sucrose at 50 mM was used. The molecular mass was estimated to be 96 kDa by SDS-PAGE and renaturation. In addition, the expression of alpha-G from 18-day and 29-day worker bees could be detected by Native-PAGE. The expression level of alpha-G cDNA was high in foragers. According to the measurement of acini, the size was increased from 3-day to 6-day worker bees but was decreased in 18-day worker bees. The alpha-G cDNA sequences (357 bp) isolated from hypopharyngeal glands were obtained by RT-PCR. Two groups were observed when maximum parsimony, UPGMA, and Neighbor joining programs were used. The first group contains all samples collected in Thailand including those from Samui Island. The other group contained samples collected in Bangkok only. The obtained cDNA sequence shows closely relationship to the cDNA in A. mellifera.