cataractogenesis is a common complication that occurs in diabetes mellitus. aldose reductase is a lens enzyme probably involved in the development of this eye problem. the purpose of this investigation was to screen plant extracts for aldose reductase inhibitors (ari) and to investigate their possible influence in diabetic cataractogenesis prevention. 13 plants and 3 natural products were randomly selected for our experiment. the 19 extracts originated from plant material which was extracted with ethanol, water and dcm, and assessed for inhibitors of aldose reductase. this enzyme was isolated from bovine lenses homogenates. the enzyme was incubated in a reaction mixture containing 50 mm na-phosphate buffer (ph 6.2), nadph, 400 mm liso4 and dl-glyceraldehyde. a spectrophotometrical assay was performed in which nadp is produced and its absorption read at 340 nm. eugenia borinquensis, mangifera indica, eucalyptus deglupta, and syzygium malaccense were among the best inhibitors. normal and diabetic sprague dawley rats were used to evaluate the in vivo effect of e. deglupta, m. indica, and e. borinquensis in cataractogenesis prevention. all of these extracts had preventive effects on the formation of cataracts. it is concluded that further investigation to explain the above findings is necessary. perhaps the next step will include an activity monitored isolation of the effective principles. future investigation will ince the isolation of the active principles in these extracts.