The biomaterial bacterial cellulose (BC) represents an innovative approach for overcoming reconstructive problems associated with extended vascular diseases by providing small caliber vascular grafts (diameter 1.0–3.7, length 5.0–10.0, and wall-thickness 0.7 mm). In a first microsurgical study, the BC implants were attached in an artificial defect of the carotid artery of rats for 1 year. These long term results show the incorporation of the BC under formation of neointima and ingrowth of active fibroblasts. In a second study, the grafts were used to replace the carotid arteries of pigs. After 3 months, these grafts were removed and analyzed both macro- and microscopically. Seven grafts (87.5%) were patent whereas one graft was found occluded. These data indicate that the innovative BC engineering technique results in the production of stable vascular conduits and confirm a highly attractive approach to in vivo tissue engineered blood vessels as part of programs in cardiovascular surgery.