on calcium oxalate crystals and to compare the effects of Plantago major extract with clinically used drugs like allopurinol and potassium citrate (positive controls). Modified Schneider slide gel method was used for the in vitro study and the crystals formed were measured by Image Analyser system KS 300, 3.0 Carl Zeiss. The concentrations of Plantago major extract used were from 100ppm to 350ppm. Plantago major extract at concentrations in the range of (100ppm-350ppm) significantly inhibited the size of calcium oxate crystals (dihydrate variety) against negative control (p