The present invention relates to an amorphous form of Sumatriptan succinate of Formula (1). The present invention also relates to process for the preparation of an amorphous form of Sumatriptan succinate. The process for the preparation of an amorphous form of Sumatriptan succinate comprises refluxing an aqueous mixture of Sumatriptan or its succinate salt in alcoholic solvents such as methanol or nitrile solvents such as acetonitrile followed by evaporation of the solvent from the filtrate. The resulting residue is triturated with water immiscible aromatic or aliphatic hydrocarbon solvents such as cyclohexane to afford an amorphous form of Sumatriptan succinate.