Percutaneous grafting of non-union using bone marrow concentrates has shown promising results, we present our experience and outcomes following the use of microdrilling and marrowstim in long bone non-unions. We retrospectively reviewed all patients undergoing a marrowstim procedure for non-union in 2011–12. Casenotes and radiographs were reviewed for all. Details of injury, previous surgery and non-union interventions together with additional procedures performed after marrowstim were recorded for all patients. The time to clinical and radiological union were noted. We identified 32 patients, in sixteen the tibia was involved in 15 the femur and in one the humerus. Ten of the 32 had undergone intervention for non-union prior to marrowstim including 4 exchange nailings, 2 nail dynamisations, 3 caption graftings, 2 compression in circular frame and 1 revision of internal fixation. Three underwent adjunctive procedures at the time of marroswstim. In 18 further procedures were required following marrowstim. In 4 this involved frame adjustment, 5 underwent exchange nailing, 4 revision internal fixation, 2 additional marrowstim, 2 autologous bone grafting and 3 a course of exogen treatment. In total 27 achieved radiological and clinical union at a mean of 9.6 months, of these ten achieved union without requiring additional intervention following marrowstim, at a mean of 5.4 months. There were no complications relating to marrowstim harvest or application. Marrowstim appears to be a safe and relatively cheap addition to the armamentarium for treatment of non-union. However many patients require further procedures in addition to marrowstim to achieve union. Furthermore given the range of procedures this cohort of patients have undergone before and after marrowstim intervention it is difficult to draw conclusions regarding it efficacy.