Validation of the ethnobotanical use of the leaves of Artemisia vulgaris Linn. (Compositae), Eucalyptus tereticornis Sm. (Myrtaceae), Solanum nigrum Linn. (Solanaceae), and Vitex negundo Linn. (Verbenaceae); stems of Nopalea cochinellifera (Linn.) Salm-Dyck (Cactaceae); roots of Imperata cylindrica Beauv. (Gramineae); dried bark of Syzygium cumini (Linn.) Skeels (Myrtaceae) as anti-diabetic agents using the oral glucose tolerance test showed that only the bark of Syzygium cumini and the leaves of Vitex negundo and Eucalyptus tereticornis exhibited anti-hyperglycemic activities when fed simultaneously with glucose. At the same dosages of 5 mg/20 g mouse, Syzygium cumini-treated mice showed a significant decrease in blood glucose levels (BGLs) at 30 min (alpha=0.10) and from 45 min onwards at alpha=0.05. Vitex negundo exhibited greater anti-hyperglycemic activity than Eucalyptus tereticornis. Both showed a significant decrease in BGLs at 60 min but at alpha=0.05 for Vitex negundo and at alpha=0.07 for Eucalyptus tereticornis. There was no significant lowering in BGLs for Imperata cylindrica and Solanum nigrum while there was even an increase in BGLs for Nopalea cochinellifera and Artemisia vulgaris.