Autologous chondrocyte implantation (ACI) techniques are becoming more popular for the treatment of full thickness cartilage lesions of the knee joint. However, there is no systematic information for the efficacy of the new generation ACI techniques compared to other treatment options. A systematic review of the existing evidence from randomized clinical trials of ACI treatment would contribute to understanding the advantages and limitations of this method and would inform the planning of future studies. Using pre-defined criteria, we searched a number of electronic databases to identify all the existing randomized control trials of any type of ACI treatment. Risk of bias was assessed and an analysis of the reported outcomes was performed. Information on the clinical efficacy and safety of ACI compared to other interventions was collected and presented. Nine trials were identified with 626 patients. Patients ranged from 15 to 52 years, and the size of treated lesions was between 1 and 22 cm(2). ACI was associated with improvement in clinical outcomes compared to baseline. However, the body of evidence did not suggest any superiority of ACI over other treatments. Complication rates were comparable between interventions except from an increased rate of graft hypertrophies after ACI with periosteum. ACI is an effective treatment for full thickness chondral defects of the knee, providing an improvement of clinical outcomes. However, there is insufficient data to say whether ACI is superior to other treatment strategies. More high quality studies and harmonization in the reported outcomes are needed before specific suggestions for practice can be made.