Category: Ankle; Sports Introduction/Purpose: Achilles tendon re-rupture (ATRR) during the subacute postoperative phase is the rupture of the repaired site combined with suture material failure induced by an unexpected traumatic event during postoperative months one to three after primary Achilles tendon repair. This study aimed to determine the effectiveness of conservative treatment for subacute ATRR. Methods: We retrospectively reviewed 390 cases (385 patients) who underwent primary Achilles tendon repair between January 2010 and August 2021. All patients had more than 12 months of follow-up and were divided into two groups based on the development of subacute ATRR (Group 1: 370 cases without ATRR; Group 2: 20 cases with ATRR). Then, we compared several outcome parameters between the groups after administering conservative treatment to those with ATRR. The baseline timepoints in Groups 1 and 2 were the primary repair and re-injury dates. Results: After primary Achilles tendon repair, 5.13% of patients experienced subacute ATRR. The time to performing a single heel raise (SHR) and performing ten repetitive SHRs did not differ between the groups (P = 0.281, 0.486). Likewise, isokinetic dynamometer results showed that the peak torque of 30o/s and 120o/s plantar flexions (the absolute value and the percentage to the contralateral side) also did not differ between the groups (P >0.05, each). However, the early Achilles tendon Total Rupture Score scale and the Foot and Ankle Ability Measure scores before six months were significantly lower in Group 2 than in Group 1 (both P < 0.05); at 12 months, the scores did not differ between the two groups (both P >0.05). Conclusion: Conservative treatment for subacute ATRR after primary Achilles tendon repair has comparable clinical outcomes to those without ATRR.