The present invention provides a parasiticidal formulation comprising: Fipronil, or a veterinarily acceptable derivative thereof at least one C1-C6 alcohol co-solvent, wherein the total amount of C1-C6 alcohol is up to 8% by weight of the formulation at least one organic solvent which is not the C1-C6 alcohol co-solvent and at least one crystallisation inhibitor, wherein the total amount of crystallisation inhibitor is from 2 to 20% by weight of the formulation. The formulations of the invention have higher flash points than known parasiticidal formulations comprising Fipronil and therefore provide safer formulations for use in the home, storage, manufacture and distribution.
