One possible strategy for creating three-dimensional (3D) tissue-engineered organs in vitro is to develop a vasculature for sufficient transport of oxygen and nutrients within these constructs. Here, we describe a novel technique to fabricate endothelialized tubes with predetermined 3D configuration, as a starting point for self-developing capillary-like networks in vitro. Calcium-alginate hydrogel fibers of ca. 250 and 500 mu m in diameter, enclosing bovine carotid artery vascular endothelial cells (BECs), were used as templates for endothelialized tubes. Fibers were prepared by extruding a 2% (w/v) sodium alginate solution containing BECs into a 100 mM calcium chloride solution flowing in the same direction. Fibers were embedded in type I collagen gels and enzymatically degraded by alginate lyase, resulting in channels with predetermined 3D configuration filled with a BEC suspension. Cells attached to and covered the surfaces of the channels. Exposing the cells to medium containing basic fibroblast growth factor resulted in their migration into the ambient collagen gel and self-assembly into capillary-like structures. These results demonstrate that using artificial endothelialized tubes with predetermined 3D configuration, as a starting point for a self-developing capillary-like network, could be potentially useful for constructing 3D tissue-engineered organs.