The hypoglycaemic efficacy of sumac (Rhus coriaria L.) and black cumin (Bunium persicum Boiss) extracts were investigated through inhibition of a glycoside hydrolase: alpha-amylase. On the basis of our result ethyl acetate extract of sumac may have interest in the treatment and prevention of hyperglycaemia, diabetes and obesity, with an IC50 value of 28.7 microg mL-1.