This study aligned Ketjen black (KB) particles along one preferred direction in a polylactic acid (PLA) matrix using an oscillatory shear flow and investigated the effect of aligned KB on the electrical anisotropy. Under the oscillatory shear, the KB particles are aligned along the flow direction in the PLA matrix, resulting in an oriented conductive network. When the concentration of KB is in the range of 0.88-1.56vol%, the electrical volume resistivity along the flow direction ((vertical bar)) decreases to approximate to 3x10(4)m and that perpendicular to the flow direction ((perpendicular to)) remains at approximate to 1x10(10)m, showing an extremely large electrical anisotropy, and the (perpendicular to)/(vertical bar) value is 3-4 orders of magnitude higher than that of previously reported carbon-nanotube-based electrical anisotropic composites. This strong anisotropy is attributed to the preferential alignment of KB particles with lower percolation threshold for conductive path along the flow direction. (c) 2015 Wiley Periodicals, Inc.