The disclosed invention is a unique drilling fluid composition and method for reducing lost mud circulation in wellbores due to seepage loss into fluid permeable subterranean formations. The drilling fluid composition comprises a variety of shapes and sizes of distinctive unadulterated elastomeric rubber particles derived from the tire retreading (recapping) process. These elastomeric rubber particles are incorporated into an aqueous, hydrocarbon, or synthetic drilling fluid in sufficient amounts as to plug holes, fractures, and fissures, form a mud cake, and thus stem the loss of drilling fluids from the lost circulation zone.
