In order to find new pancreatic lipase (PL) and α-amylase inhibitors from natural sources for the treatment of obesity and related diseases as diabetes mellitus II, 23 medicinal plants with weight-reducing, serum glucose-reducing or related potential were investigated. Methanolic and water extracts of the plants were evaluated by using two in vitro test systems. Our findings have shown that the methanolic extract of Hibiscus sabdariffa L. (Malvaceae) showed high inhibitory activities to PL (IC50: 35.8 ± 0.8 μg/mL) and α-amylase (IC50: 29.3 ± 0.5 μg/mL). Furthermore, the methanolic extract of Tamarindus indica L. (Leguminosae) showed a high anti-lipase (IC50: 152.0 ± 7.0 μg/mL) and the aqueous extract a high anti-amylase (IC50: 139.4 ± 9.0 μg/mL) activity. This work provides a priority list of interesting plants for further study with respect to the treatment of obesity and associated diseases. Copyright © 2015 John Wiley & Sons, Ltd.