OBJECTIVES This paper aims to evaluate if any ultrasonographic aspect of metacarpo-phalangeal (MCP) joint can be predictors for the development of new joint damage, at single joint level, in rheumatoid arthritis (RA) patients. METHODS Two hundred and forty MCP joints of 24 patients with RA were prospectively evaluated both clinically and by ultrasound (US) at time 0, at six months and 12 months, in order to collect the following variables: presence of synovial hypertrophy and power-Doppler (PD) vascularisation both graded on a semiquantitative (0-3) scale, and the number and dimension of bone erosions. X-ray examinations were carried out at time 0 and at 12 months and lesions were graded using the Sharp/van der Heijde (S/vdH) method at single joint level. Potential prognostic determinants for joint damage obtained at the first examination and during follow-up were entered in a conditional logistic regression analysis. RESULTS Fifteen out of seventeen (88%) of the new eroded joints on x-rays examination had persistent PD vascularity and 14/17 (82%) had persistent synovial thickening (p=0.001 and p=0.02, vs. non-eroded joints, respectively). In multiple conditional logistic regression analysis, the most important factor associated with the development of radiological joint damage was the presence of a synovial PD score ≥2 on two or more US evaluations (OR 8.51 [95%CI 1.84-39.48] for Rx new erosions and OR 8.30 [95%CI 1.97-38.9] for increased S/vdH local joint score). Both baseline synovial score ≥2 and presence of Rx erosions were also significantly associated with the development of radiological joint damage. Two predictive models for x-ray erosions and total single joint level S/vdH damage score were constructed consisting of 2 baseline plus one longitudinal variable with a ROC AUC of 0.916 (95%CI 0.867-0.965) and 0.886 (95%CI 0.814-0.957). CONCLUSIONS At the single joint level, the presence of US determined synovial thickness and PD signal at baseline and the persistent PD signal over time have relevant prognostic value for the development of articular damage in the same MCP joints of RA patients.