Background Only a few studies exist that have assessed the efficacy of autologous osteochondral transplantation (AOT) treatment of osteonecrosis (ON) of the knee. The purpose of this study was to clarify the clinical and radiographic results of AOT performed on young patients with postcollapse ON of the knee. Methods This retrospective study included 14 young patients (6 men, 8 women, mean age 34.71 +/- 5.41 years) with stage III knee ON undergoing AOT surgery. Mean follow-up time was 87 +/- 10.23 months. The postoperative clinical and radiological evaluations were based on Hospital for Special Surgery (HSS) scores and plain x-rays. Paired t tests were used for the statistical analysis by SPSS software. Results Preoperative HSS (mean 66.86 +/- 7.49 points) was significantly improved at mean 7 years to a postoperative HSS (mean 87.36 +/- 8.63 points) (P < 0.001). The postoperative rangeof motion (ROM; 125.71 degrees +/- 4.74 degrees) was not significantly different from the preoperative ROM (126.86 degrees +/- 7.13 degrees) (P = 0.626). There was no progression of collapse observed in any knees at the last follow-up. No knees required any reoperations during the follow-up period. Conclusion Fourteen young patients with local ON of the knee were treated by AOT. No progression of bone collapse was seen and clinical improvement sustained at mean 7 years postsurgery. AOT seems to be a safe technique that can give long-term improvement and durability in young ON patients. However, large-sample and high-quality clinical trials are still needed in the future.