Hyperuricemia is a common metabolic disorder and several herbal formulations are being used for its treatment. The study aimed to develop herbal formulation (Urinil B) and find its hypouricemic effects in vitro and in vivo. Urinil B was prepared by taking Trachyspermum ammi, Piper nigrum and Berberis vulgaris equally. In vitro Dissolution test and xanthine oxidase inhibition assay was performed for checking capsule absorbance and IC50 calculation respectively. For in vivo experimentation, the study comprised of 14 groups of rats (n=6). Results showed that significant xanthine oxidase inhibition was shown by herbal formulation with IC50 of 586±1.5μg/mL. Oral administration of Urinil B 250, 500 and 1000 mg/kg decreased serum and liver uric acid levels of hyperuricemic rats in dose and time dependent manner. 3 day and seven day administration of Urinil B reduced serum and liver uric acid level more significantly as compared to one day administration. However, allopurinol normalized serum and liver uric acid levels in all study groups. The present study indicated marked hypouricemic effects of Urinil B in hyperuricemia induced by potassium oxonate in rats. However, due to caveat of small sample size in this study, clear conclusion regarding hypouricemic potential of Urinil B can't be made.