We report on the preparation of electropositive nanofiber membranes by electrospinning with in situ photo-crosslinking and their preliminary evaluation in virus adsorption and removal tests. Poly(vinyl alcohol) (PVA) and polyethyleneimine (PEI) were modified with glycidyl methacrylate, to form an acrylated crosslinked polymer (a-PVA/a-PEI) upon UV exposure during the electrospinning process. The a-PVA/a-PEI nanofibers were electrospun on a non-woven polyester support to form an electropositive (zeta = 7 mV at pH 7.4) and hydrophilic (theta(w) similar to 53 degrees) membrane with the mean pore size of 0.48 mu m. The microfilter had the specific permeate flux of similar to 6.9.10(4) L/(m(2).h.bar), comparable with that of commercially available membranes of similar nominal pore sizes. Adsorption of the negatively charged and hydrophilic bacteriophage MS2 (d similar to 27 nm) onto the membrane followed Freundlich isotherm and could be classified as favorable with the average adsorption intensity n(-1) similar to 0.91. The 99% retention of MS2 in flow-through virus clearance tests was attributed to adsorption and was likely controlled by the limited detention time within the membrane.