Background: Twenty patients with twenty primary osteoarthritic knees underwent Arthroscopic Subchondral Drilling (ASD) in combination with Autologous Bone Marrow Stem cells (ABMSCs) injection from pelvis. Objectives: 1) Investigate some indexes of ABMSCs block of patients with KOA and 2) Evaluate the initial results of KOA's treatment by ASD and ABMSCs injection. Subjects and Methods: Twenty primary KOA underwent ASD in combination with ABMSCs injection from pelvis. Most of knees had grade 3 chondral lesions. Results: The number of CD34( +) cells obtained in Autologous Bone Marrow blocks average 5.5 x l0 exponent 6. The number of cells that create clusters of CFU-F average 21 x l0 exponent 3. In the followup time after surgery as early as 6 weeks, the longest was 24 weeks, all twenty patients started showing signs of clinical improvement, there were no case of infection complications, postoperative adhesive knee. Conclusion: This is a new method of treating KOA, safe, minimally invasive and effective long-term, due to stem cell can regenerate and differentiate into chondrocyte, help repair damaged cartilage. The successfulness of this method has opened a new perspective in the treatment of KOA and help prolong or avoid knee replacement surgery.