Chondrocytes transplantation in articular cartilage regeneration combines new and recent surgical and scientific advancements in cell therapy which is used to treat acute or overuse injuries of the articular cartilage. This surgical technique is called Autologous Chondrocyte Implantation (ACI) and has been performed, studied and improved over the last thirty years. Autologous Chondrocyte Implantation is done by harvesting chondrocytes from a healthy area of the cartilage, then the chondrocytes are cultured in a laboratory, before being implanted again in the area of the injured cartilage. ACI is a surgical procedure that mainly targets the repair and regeneration of the articular cartilage of the knee joint. This procedure can be performed with three slightly different modifications known as three generations. While first generation includes placing a periosteal cover over the defect area of cartilage to house the autologous chondrocytes, second generation uses a collagen membrane as a cover instead of the periosteal cover from the first generation. The third generation is based on biomaterials in which the autologous chondrocytes are embedded before being implanted to the area of the defect. ACI is the topic of many studies which try to conclude how does this technique fit in the world of articular cartilage surgery, meaning how does this procedure compete with other different available procedures. First, studies were being done to measure the short and mid-term effectiveness of the surgery while later as the different generations emerged studies focused on challenging them against one another. Finally, and still on-going, ACI is being tested and studied in the long-term post-surgery period, to measure the success and the incidence of osteoarthritis as well as preserved function of the joint. ACI is an expensive option for the patients and also requires them to be actively and highly involved in the long process of physical therapy and rehabilitation. It was concluded at this point that ACI is an effective technique both in the short and mid-term periods as well as the long-term periods post-surgery. Many of the patients that were studied reported excellent or good outcomes and this is also supported with the data provided by clinical scoring methods and imaging done during this studies.