Autologous stem cell therapy in the field of regenerative veterinary medicine involves harvesting tissue, such as fat, from the patient, isolating the stem and regenerative cells, and administering the cells back to the patient. Autologous adipose-derived stem cell therapy has been commercially available since 2003, and the current study evaluated such therapy in dogs with chronic osteoarthritis of the hip. Dogs treated with adipose-derived stem cell therapy had significantly improved scores for lameness and the compiled scores for lameness, pain, and range of motion compared with control dogs. This is the first randomized, blinded, placebo-controlled clinical trial reporting on the effectiveness of stem cell therapy in dogs.