Urinary lithiasis is a widespread condition that affects 4 to 18% of the population, depending on the country. This pathology requires a great deal of multidisciplinary research. The work presented in this book aims to clarify the nature of urinary stones in eastern Algeria and then to study the role of certain trace elements and the effect of some medicinal plant extracts on the dissolution of urinary stones. The techniques used are mainly the following: Fourier transform infrared spectrophotometry to determine the chemical composition of the stones, X-ray fluorescence to determine the nature and content of trace elements, and scanning electron microscopy to explore the intimate structure of the crystallites at the mesoscopic scale. Other methods, such as optical microscopy, were used to perform a morphoconstitutional analysis of the stones. Finally, an in vitro experimental model was developed to study the effect of medicinal plants. Although the number of urinary stones considered was small, the epidemiology of lithiasis in this region of Algeria was outlined.