Objective: One of the most common psychiatric disorders in children is ADHD (Attention Deficit Hyperactivity Disorder), which is treated extensively by Methylphenidate. This study investigates the assessment of the effects of methylfenidate on Histopathologic and Histomorphometric changes of testes and serum level of gonadotropin in adulthood which produces gametes and has Importance for future generations. Method: In this study 36 adult male mice (Balb/C) were used. After determining the body weight, the animals were divided randomly into two experimental groups of and one control group. The Experimental groups received Ritalin via gavage as follow: The group 1 received 2 mg/kg/day and the group 2 received 10 mg/kg/ day for a period of 40 days. After evaluation of body weight, general anesthesia was used for taking blood samples from the heart in order to measure gonadothropins levels in serum. Then for the purpose of body weighing and measuring of diameter of germinal epithelium the testes were removed and the possibility of any pathologic changes was considered. Results: The results showed that Methylphenidate with different doses could decrease germinal epithelium and also body weight significantly. Besides some significant changes in serum gonadotropins, without any pathological changes were observed. Conclusion: Our findings demonstrated that Methylphenidate administration in adulthood due to Influence of enhanced computed tomography and magnetic resonance imaging was characterized as 8×8×7 cm sized welldemarcated left renal middle-superior polar mass with central necrosis and cystic changes. The contralateral kidney was normal. He underwent left radical nephrectomy by thoracoabdominal approach. Gross examination of the specimen revealed yellowish white 9×9×7 cm sized mass, with multifocal necrozis and cystic changes. Histopathology of these resection specimens; scattered spindle cells and foam cells, fine vascular network and necrosis. Immunohistochemistry revealed CD68-positive xanthoma cells. The tumor also stained positive for vimentin, CD34, but negative for cytokeratin, EMA, desmin, SMA and myoD1. A diagnosis of MFH was made. Conclusion: MFH is a primitive mesenchymal tumor with some histiosytic and fibroblastic differentiation Primary renal MFH is an extremely rare lesion. Because this malign mesenchymal tumor is indistinguishable clinically and radiologically from renal cell carcinoma diagnosis and histopathology of this rare lesion are discussed.