Urolithiasis is defined as the result of abnormal development of the normal constituents of urine within the urinary tract. For a long time, it was called stone sickness, from the Greek "lithos" which means stone. Calcium-calcium lithiasis formed from calcium (Ca) and oxalate (Ox) are by far the most common. The present work is devoted to the study of the inhibitory effect of crystalluria, which may be present in aqueous extracts of fruit byproducts such as carob, lemon and orange pulp. The objective is that the valorization of its agrifood by-products may be related to the antilithiasic effect of their aqueous extracts. Urine samples from human patients were collected in the Regional Hospital Center of the Beni Mellal-Khénifra area in Morocco. The identification of crystalluria and the enumeration of the identified crystals was carried out by polarizing light optical microscope (PLOM). Solutions of aqueous extracts of the pulps of the three fruits were prepared at different concentrations to evaluate the count, on the PLOM, of calcium oxalate crystals formed. The pulps of the three by-products (carob, lemon and orange) have an inhibitory effect for the formation of crystals, especially in the case of lemon. According to the obtained results, it is found that at the 0.25 g / l concentration of the aqueous extract, for each of the three types of carob, lemon and orange pulp, around 50% of the number of the calcium oxalate disappears. In addition, it is found that for the aqueous extract of carob pulp at the three concentrations 0.25, 0.125 and 0.0625 g / l, comparing the results on the aqueous solution of calcium oxalate and the urine of the patient lithiasic, we note that the inhibitory effect is not clear. However, the two extracts of lemon and orange pulps have an inhibitory effect on crystalluria for the three concentrations of the extracts.