The hypoglycemic effect of a water extract from aerial parts (0.33 g/kg) of Equisetum myriochaetum Schlecht and Cham (Equisetaceae) was analyzed in 11 recently diagnosed type 2 diabetic patients. A single dose of this extract was orally administered. Glucose and insulin were determined at 0, 30, 60, 90,120 and 180 min after administration. The same patients served as the control group and received only colored water as placebo. The administration of the extract significantly reduced the blood glucose levels of the type 2 diabetic patients within 90, 120 and 180 min. There were no significant changes in the insulin levels. The results demonstrate that the water extract of the aerial parts of E. myriochaetum shows a hypoglycemic effect in type 2 diabetic patients starting 90 min after its administration.