Arrays of nickel nanowires with aspect ratio of 1200 and diameters ranging between 25 and 100 nm have been fabricated by electrodeposition in etched ion track templates. Samples with different areal densities ranging from 1 x 10(6) cm(-2) to 1 x 10(8) cm(-2) have been prepared for this study. Magnetic measurements were performed at room temperature for different aspect ratios and diameters of the wires. Coercivity of the wires showed a strong dependence on aspect ratio (I/d), diameter and microstructure. In the case of parallel applied field coercivity of the wires has maximum value at similar to 40 nm diameter. The wires with high areal densities showed relatively lower coercivities as compared to the low density samples. The results have been discussed by taking into account various magnetic anisotropies originating from the shape and crystalline nature of the wires, and the magnetostatic interactions among the wires. (C) 2011 Elsevier B.V. All rights reserved.