This study was performed to investigate the safety and efficacy of the intra-articular infusion of ex vivo expanded autologous bone marrow-derived mesenchymal stem cells (BM-MSC) to a cohort of patients with articular cartilage defects in the hip. The above rationale is sustained by the notion that MSCs express a chondrocyte differential potential and produce extracellular matrix molecules as well as regulatory signals, that may well contribute to cure the function of the damaged hip joint. A cohort of 10 patients with functional and radiological evidences of hip osteoarthritis, either in one or both legs, was included in the study. BM-MSC (the cell product) were prepared and infused into the damaged articulation(s) of each patient (60 × 106 cells in 3 weekly/doses). Before and after completion of the cell infusion scheme, patients were evaluated (hip scores for pain, stiffness, physical function, range of motion), to assess whether the infusion of the respective cell product was beneficial. The intra-articular injection of three consecutive weekly doses of ex vivo expanded autologous BM-MSC to patients with articular cartilage defects in the hip and proved to be a safe and clinically effective treatment in the restoration of hip function and range of motion. In addition, the statistical significance of the above data is in line with the observation that the radiographic scores (Tönnis Classification of Osteoarthritis) of the damaged leg(s) remained without variation in 9 out of 10 patients, after the administration of the cell product.