Urolithiasis, the category of diseases associated with the formation of kidney stones, has many causes. However, only a few have been documented as aggravating calculi depositions and aggregations. This amply justifies continued work in developing effective and efficient inhibition and treatment techniques. The recent resurgence in reviews on plant antiurolithiatic activity has given credence to the application of modern spectroscopic analysis, and has led us to this study. Results obtained from Raman and infrared (IR) absorption analysis of inhibited calculi growth resulting from laboratory synthesis of calcium oxalate crystals accompanied by the natural infusion of Larrea tridentata are reported. A visible decrease in calcium oxalate crystal growth with increasing amounts of L. tridentata herbal infusion was observed in photomicrographs, as well as a color change from white-transparent for pure crystals to light orange-brown for crystals with inhibitor. Both Raman and IR absorption spectra reveal a monohydrate structure for the crystals grown alone, which transform to a dihydrate morphology with the addition of the L. tridentata inhibitor. Furthermore, the resulting data support the possibilities of the influences, in this complex process, of the nordihydroguaiaretic acid (NDGA) and its derivative compounds from L. tridentata and the bonding of the magnesium of the inhibitor with the oxalate ion on the surface of the calculi crystals. This assumption corroborates well with the micrographs obtained under higher magnification, which show that the separated small crystallites consist of a darker brownish core, which we attribute to the dominance of growth inhibition by NDGA, surrounded by light transparent thin shells, which possibly correspond to passivation of the crystals by magnesium oxalate. Copyright © 2010 John Wiley & Sons, Ltd.