Methylphenidate is a psychostimulant used for the treatment of (ADHD) attention deficit hyperactivity syndrome in children and adults. After chronic administration it is known to produce behavioral disorders including anxiety. Previous studies demonstrated that co-administration of buspirone can reduce behavioral and cognitive adverse effects produced by methylphenidate. The aim of the present study is to measure the levels vanillylmandelic acid (VMA) excretion in urine following prolong administration of methylphenidate, buspirone and their combination. Samples of urine for the estimation of the urinary VMA excretion were collected from treated and control male Wistar rats. We found significant (P<0.01) raised urinary VMA excretion in methylphenidate group however significant (P<0.01) reduction in VMA levels were seen after buspirone co-administration. Excretion of VMA in urine would allow the monitoring of sympatho-adrenomedullary system activity. This study could be helpful to increase the clinical use of methylphenidate in the treatment of different disoders.