In this study, the twenty-four ethyl acetate extracts of twenty-two medicinal plants, traditionally used in Vietnam as anti-diabetes agents, were investigated for ${alpha}$-amylase and protein tyrosine phosphatase 1B (PTP1B) enzymes inhibitory activity in vitro. The results indicated that, twelve materials (50.0%) showed moderate to strong inhibitory activity in ${alpha}$-amylase inhibitory activity with $IC_{50}$ values ranging from 2.5 to $48.8{mu}g/mL$; meanwhile, ten extracts (41.6%) could demonstrate PTP1B activity with $IC_{50}$ values less than $30.5{mu}g/mL$. Some plants presented interesting activities against both of ${alpha}$-amylase and PTP1B enzymes such as Catharanthus roseus, Carthamus tinctorius, Momordica charantia, Gynostemma pentaphyllum, Glycyrrhiza glabra, Smilax glabra, Psidium guajava (leave), and Rehmannia glutinosa. The study may provide a proof, at least in a part, for the ethno-medical use in diabetes disease of these plants.