Ultrafine 1,6-diisocyanatohexane-extended poly(1,4-butylene succinate) (PBSu-DCH) fibers were best fabricated by electrospinning from 22% w/v PBSu-DCH solution in 90:10 v/v dichloromethane/trifluoroacetic acid under the electric field of 17 kV/20 cm. The diameters of these fibers were 172 +/- 3 nm. Due to their fibrous nature, the obtained PBSu-DCH fiber mats exhibited high values of advancing/receding water contact angles (i.e., 114 degrees/79 degrees) and porosity (69%). Indirect cytotoxicity evaluation of the PBSu-DCH fiber mats based on the viabilities of human osteosarcoma cells (SaOS-2) and mouse fibroblasts (L929) revealed that the fibrous materials did not release any substance in the level that was harmful to the cells. The potential for use of the PBSu-DCH fiber mats as substrates for bone cell culture was further evaluated in vitro with SaOS-2 in terms of the ability to support the attachment and to promote the proliferation and the differentiation of the seeded/cultured cells. Comparative studies were made against corresponding solvent-cast PBSu-DCH films. The results indicated that the bone cells grown on the surface of the fiber mats could attach, proliferate and express alkaline phosphatase (ALP), an early osteogenic proliferation marker, better than they did on the surface of the films. The evidence obtained in this work implies the potential for use of the electrospun PBSu-DCH fiber mats as bone scaffolds. (C) 2009 Elsevier Ltd. All rights reserved.