Arthroscopic meniscal repair has been a common procedure for the treatment of a torn meniscus, since the importance of meniscal preservation is widely understood. Over the years, the complications associated with suture material have been reported. Meniscal cyst is also one of those things. But ganglion cyst triggered by non-absorbable suture material was not documented in the literature. We report the case of a 19-year-old boy who underwent arthroscopic ACL reconstruction and repair of the medial meniscus by inside-out technique using 2-0 non-absorbable polyester sutures. The patient returned to our clinic at 4-year F/U with right knee pain due to medial meniscus tear and ganglion cyst. We suspect non-absorbable suture materials itself might have caused soft tissue irritation with repetitive trauma that lead to mucoid degeneration which results in ganglion cyst formation in the end.