Bead milling was used to produce nano silk particles from silk fibres. Silk fibres were first milled to volume median particle size d(0.5) of 7 mu m using an attritor mill. It was followed by bead milling to prepare submicron particles. Several processing parameters including milling speed, milling time, bead load, and pH were examined to reduce the particle size in the bead mill. It was found that, at pH 10 and using optimized milling parameters, d(0.5) could be reduced from 7 mu m down to about 200 nm, with a narrow particle size distribution. (c) 2013 Elsevier B.V. All rights reserved.