By the use of a high-speed collection drum, poly(vinylidene fluoride) (PVDF) was electrospun into aligned ultrafine fibrous membranes from its solutions in a mixture of N,N-dimethylformamide and acetone (9:1, v/v), and a continuous hot-press post-treatment was performed on the membranes to improve their mechanical properties. Anisotropic tensile results and rupture behaviors of the hot-pressed PVDF membranes with higher fiber alignments in both revolving direction (RD) and cross direction were obtained. It was found that, due to the true fracture of electrospun fibers and improvement of the interfiber compaction by hot-press, the tensile strength and modulus of the hot-pressed membranes in RD reached the highest values at 58.12 +/- 4.46 MPa and 519.9 +/- 34.1 MPa, respectively when the collection speed was 10.42 m/s. The decrease of porosity and liquid absorption also represented the compaction improvement of the electrospun fibrous membranes. The combination of fiber alignments and hot-press could provide a novel method to fabricate high strength of electrospun membranes which have highly potential applications in filtration or battery separators. POLYM. ENG. SCI., 49:1291-1298, 2009. (C) 2009 Society of Plastics Engineers