Chemical composition analysis of urinary stones is a fundamental part of the metabolic workup of urolithiasis.To report the chemical composition of urinary stones using infrared spectroscopy.The chemical composition of rinary stones recovered from 649 patients aged 1 to 97 years (68% males), were analyzed using a Perkin Elmer FTIR Spectrometer, Spectrum Two.Calcium oxalate monohydrate was the most common composition found in 45% of cases, followed by mixed composition, which included three ammonium phosphate stones in 29% of cases. Pure uric acid composition was found in 16% of stones. Three cystine stones were detected.These findings do not differ from those found in developed countries.