Ruptures of tendons and ligaments are a widely common injury in traumatology. The aim of the study was the development of a substitute tissue for such defects by methods of tissue-engineering. Human bone marrow stromal cells (hBMSC) were seeded on a decellularized bovine Achilles tendon and cultivated in a special bioreactor. We examined the influence of continuous perfusion on proliferation and biomechanical stability compared to static cultivation. Samples were taken on day 0, 7 and 14. Decellularized tendons were chosen as a negative control. Cell quantity was measured by the MTS-Test. Histology was analyzed by Haematoxylin-Eosin- and Pentachrome-coulouring. The cultivated tendons were tested biomechanically compared with the decellularized control group. MTS-Test revealed an increase of cell count of 7% in the static group and a decrease of 9% in the perfusion group. The perfusion group showed a stronger network of the fibroblasts and a higher amount of produced extracellular matrix. Biomechanical testing revealed significantly higher stability in the decellularized control group. This trial shows up new possibilities of managing defects of tendons and ligaments. The continuous perfusion in a bioreactor can improve the structure of the matrix seeded with hBMSC.