Newly synthesized polymercaptal microspheres of 0.8 +/- 0.02 micron were shown to have a specific and fast intake of mercury compounds over a whole range of pH while maintaining low toxicity. The microspheres bind easily with mercury compounds which are already bound to the biological mercury binders, albumin or cysteine. Mercury was recovered completely from the microspheres by using a solution of thiourea in hydrochloric acid. Due to their high surface area, low toxicity, and strong affinity toward mercury compounds, the microspheres have a potential use as a new oral drug for treatment in cases of mercury poisoning.