Analytical method was developed for the estimation of Risperidone drug substance by High Performance liquid chromatography. The chromatographic separation was achieved on C8 column (Zodiac 100, 150×4.6mm, 5um) at ambient temperature, the separation achieved employing a mobile phase consists of 0.1%v/v Ammonium formate in water: Methanol (30:70). The flow rate was 1.0 ml/ minute and ultra violet detector at 240nm. The average retention time for Risperidone found to be 3.52 min the proposed method was validated for selectivity, precision, linearity and accuracy. All validation parameters were within the acceptable range. Antipsychotic drug tend to block dopamine D2 receptor in dopaminergic pathways of brain this means that dopamine released in these pathway has less effect. Excess release of dopamine in the mesolimbic pathway has been linked to psychotic experience decreased dopamine released in other pathway are associated with psychotic episodes in schizophrenia and bipolar disorder. Keywords:- Risperidone, HPLC, C8, Ammonium formate, Validation etc.