Pretibial cyst formation following anterior cruciate ligament (ACL) reconstruction is infrequent. This article describes a case of pretibial cyst, following ACL reconstruction. The patient complained of painless mass localized on the anteromedial aspect of the ipsilateral proximal tibia 2 years after ACL reconstruction. No inflammatory reaction or graft insufficiency were detected. The patient underwent cyst excision and curettage of the lower tibial tunnel. No communication between the tibial tunnel and joint space was confirmed arthroscopically. Histologic observation revealed particulate debirs associated inflammatory giant cells, suggesting ongoing degradation of the bioabsorbable interference screw. These findings indicated that mechanical irritation of bioabsorbable screws appeared to stimulate the foreign body reaction and may have caused the pretibial cyst formation after ACL reconstruction.