To evaluate by second-look arthroscopy the clinical results of arthroscopic all-inside sutures with hook using 2 posteromedial portals for medial meniscus posterior horn (MMPH) tears in patients who underwent concurrent anterior cruciate ligament (ACL) reconstruction. Case series. From May 1997 to June 2001, 78 knees underwent surgery for MMPH tears with arthroscopic all-inside sutures with hook and concurrent ACL reconstruction. Among them, 39 patients were evaluated with follow-up second-look arthroscopy. All MMPH tears were repaired by arthroscopic all-inside suture technique using 2 posteromedial portals. The second-look arthroscopy was performed, on average, 19 months (range, 6 to 40 months) after the ACL reconstruction and meniscal repair. They were divided into complete healing, incomplete healing, and failure groups. Tear size, type, and location were analyzed. We determined clinical criteria for success in meniscal status as (1) not positive for 4 clinical objective parameters--joint line pain and tenderness, locking or catching, recurrent effusions, and McMurray test; and (2) complete healing of all-inside sutured meniscus during second-look arthroscopy. Among 39 knees assessed by second-look arthroscopy, 32 (82.1%) knees showed complete healing and 6 (15.4%) showed incomplete healing without any positive findings of the clinical symptoms. Furthermore, all cases in the incompletely healed group had complete healing of the posterior horn, which was sutured by an all-inside suture; the incomplete healing was observed between the junction areas of all-inside to inside-out sutures, which was mainly at the posteromedial corner. The success rate was 97.4% (38 of 39 patients) overall for all-inside suture healing. The 1 patient (2.6%) with clinical failure had a retear of the repaired site. The average knee scores improved and all showed less than 2-mm side-to-side difference on KT-2000 testing. Arthroscopic all-inside vertical suture using a suture hook resulted in a high rate of healing even in large and complex vertical tears. This suturing can be one of the optimal treatments for MMPH tears greater than 1 cm during concurrent ACL reconstruction. Level IV, Therapeutic Study, Cases Series (no, or historical, control group).