of economics availability at any drilling site and performance diesel oil is most preferred synthetic oils however are preferred where environmental impact is a concern the drilling fluid additives of the present invention can be used in both hydrocarbon based and aqueous or water based drilling fluids if polymer expansion is needed in an aqueous system a hydrocarbon fluid must be added to the elastomer particles to achieve the desired expansion it has been observed however that improved fluid loss can be achieved in aqueous drilling fluids without adding a hydrocarbon fluid the improved fluid loss reduction is achieved by the ability to use higher amounts of particles one method for practicing this invention involves the injection of a discrete pill of drilling fluid containing the drilling fluid additives of the invention in a sufficient amount to seal off the lost circulation zone this pill is then forced down to the lost circulation zone the elastomer particles then fill the holes and fractures preventing loss of the fluid depending upon the polymer and the composition of the drilling fluid about two to about 250 pounds of polymer per barrel of fluid can be placed in the pill methods for introducing the pill containing the drilling fluid additive of the invention are well known to those in the art other matter may be added to the pill to enhance the sealing properties of the fluid for example cellulose fiber from plant matter such as peanut shells sugar cane husks or bagasse almond shells walnut shells dried tumbleweed and paper may be added to the pill bridging materials such as calcium carbonate may also be added coarse and fine.