Abstract: The environmentally safe filtration control agent for drilling fluids is an additive for aqueous drilling fluids to reduce the loss of fluids from the mud cake to the pores of the formation during the drilling of oil and gas wells. The additive may be powdered grass formed by drying grass and grinding the dried grass to micron-sized particles; date seed powder formed by grinding the seeds of date plants to micron-sized particles; or grass ash powder formed by dried grass burnt in a furnace and ground to micron-sized particles. The filtration control agent is generally present in the drilling fluid as a concentration between 0.25 ppb and 2 ppb, optimally between 1.0 ppb and 2.0 ppb, depending on the agent. An exemplary drilling fluid includes water, bentonite, and the fluid control agent.