Background/Aim Preliminary data suggest that an intraarticular autologous fat transplant may be useful in osteoarthritis (OA) of the CMC-1 joint. This prospective, non-randomised pilot study investigates this new method with a view to clinical outcomes compared with intraarticular corticosteroid injection. Patients and Methods 17 women and 7 men with an average age of 63.3 (47-75) years with symptomatic OA were included in the study. In 12 patients, a radiologically guided injection of 1-1.5 ml of adipose tissue was carried out after transumbilical liposuction of 10 ml of abdominal fat. Prior to that, the fat was homogenised using two Luer-Lock Syringes, but not centrifuged. Postoperatively, the thumb was immobilised for one week. The patients from the cortisone control group received an intraarticular injection of 10 mg (1 ml) of Triamcinolon® under sterile conditions without subsequent immobilisation. Preoperatively as well as 2, 6 and 12 weeks postoperatively, the QuickDASH and the Michigan-Hand-Questionnaire (MHQ) were analysed, the pain was measured by means of the visual analogue scale (VAS), and strength and grip force were measured. Results Both the cortisone group and the autologous fat group showed a significant reduction in stress pain after two weeks. Both methods had no significant effect on force. The evaluation of quality of life by means of QuickDASH and MHQ after cortisone treatment initially demonstrated an improvement in quality of life, which, however, fell below the previous level after 6 weeks. After autologous fat transplantation, quality of life increased continuously. Conclusion In contrast to cortisone injection treatment, a persistent pain reduction was achieved in the fat injection group in the 3-month follow-up period, whereas cortisone injection only resulted in a short-term reduction of pain lasting about 6 weeks. Long-term follow-up is required now to show how long the effect of autologous fat transplantation in OA can be sustained.