The inhibitory effects of 40 extracts prepared from 38 traditional Turkish folk medicines on human aldose reductase (h-AR) and hematological activity were investigated. Seven plants containing 5 species of Cistus genus exhibited a potent inhibition of h-AR. Ferulago amani (root) inhibited the platelet aggregation induced by sodium arachidonate, while C. laurifolius (fruit) was found to possess strong inhibition in the blood coagulation assay. An AcOEt extract derived from the leaf of C. laurifolius was purified to isolate three known flavonoids. The activity of one, quercetin-3- O -methyl ether, was found to be as potent as that of eparlestat, which is known to be a remedy for treating complications associated with diabetes.