The aim of this study was to estimate the mechanical properties and evaluate the biocompatibility of silk and PGA scaffolds as an artificial ligament to an ACL reconstruction. The scaffold for the artificial ligament was braided / knitted silk or PGA thread. The mechanical properties, cell growth, and subcutaneous tissue reactions were determined for both types of scaffolds. The breaking load of the PGA scaffold was double that of the sericin removed silk scaffold (SRSS). However, the initial attachment and growth of human ACL cells on the SRSS was superior to the PGA scaffold. In addition, the immune response was significantly higher on the PGA scaffold after 72 h (p<0.05) compared with the sericin removed silk scaffold by T lymphocyte and mononuclear cells (MNCs) in vitro cultures. In vivo, the ACL scaffold made from silk or PGA were implanted in the subcutaneous layer in rats and harvested 1 week later. A histological evaluation of the scaffolds explants revealed the presence of monocytes in the SRSS, and an absence of giant cells in all cases. An inflammatory tissue reaction was more conspicuous around the silk scaffold containing sericin and even more around the PGA scaffold compared with SRSS. These results support the conclusion that a properly prepared SRSS, aside from providing benefits in terms of biocompatibility both in vitro and in vivo, can provide suitable scaffolds for the support of ACL cell growth. These results suggest that a SRSS for ACL repair can overcome the current limitations with the PGA scaffold. And SRSS is biocompatible, and the in vitro T cell and MNCs culture model showed inflammatory responses that were comparable to those observed in vivo.