Chrysotile was treated using three methods to reduce its toxicity and prepare it for use as nanofiller in olefin polymerization. In two of the treatments chrysotile was leached with hydrochloric acid at different concentrations, 0.1 and 3.0 M, and subsequently subjected to thermal treatment. In the third method the chrysotile was only exposed to a thermal treatment at 800 °C. The treated chrysotiles were characterized by BET, SEM-EDX, XRD, TEM and DRIFTS. The dilute acid treatment was the most efficient and gave a material with a nanotube morphology, with reduced toxicity, high aspect ratio and high concentrations of isolated OH groups. All the treatments gave particles with nanometric dimensions interesting for use as nanofillers in nanocomposites and also as support for catalysts.