Pseudoarthrosis or non union is a complication wich incidence is estimated around 5-10% of fractures. Its frequently located in diaphysis of long bones. It is a complication that requires important surgical procedures and a worrying problem in orthopedic and trauma surgery actually. The discovery of a molecule or biomarker to detect those patients at risk of develope a delayed bone healing or non union would help us to establish special measures for their treatment.earlier. MATERIAL AND METHODS We propose a prospective exploratory pilot study that analyzes a cohort of 20 patients diagnosed of non-hypertrophic non-union of long bones undergoing surgical treatment consisting in autologus bone graft +/- re osteosynthesis. These patients were followed for 12 months. Plasma blood samples were obtained to determine Tranforming Growth Factor B1 and B2 (TGF-B1, TGF-B2) at inclusion, at week, 2 weeks, 1 month, 2 months, 3 months, 6 months and 12 months after surgery. Radiological bone healing was evaluated by the Tomographic Union Score (TUS). RESULTS 20 patients were included, 17 were analyzed finally. 9 healed versus 8 that did not heal. The mean values of TGF-B1 at inclusión time point were: 26,702.4 +/- 14537 pg / ml. For TGF-B2: 307.8 +/- 83.1 pg / ml. Statistically significant differences were found between the bone healing group and the non-union group at 12 months for TGF-B1 (p 0.005). No significant differences were found between the two groups for TGF-B2. CONCLUSIONS TGF-B1 can be a serological marker of bone healing although we can not say that it is a biomarker that allows early detection of delayed unión or non unión in base of our results. The same conclusion would be applicable to TGF-B2.