Radial head fractures are common and mainly require a functional conservative treatment. About 20% of patients will present an unsatisfactory final functional result. There is, however, little data allowing us to predict which patients are at risk of bad evolve. This makes it difficult to optimize our therapeutic strategies in these patients. The aim of this study is to determine the personal and environmental factors that influence the functional prognosis of patients with a radial head fracture. We realized over a 1-year period a prospective observational longitudinal cohort study including 125 consecutive patients referred for a fracture of the radial head in a tertiary trauma center. We originally collected the factors believed to be prognostic indicators: age, sex, socioeconomic status, factors related to trauma or fracture, alcohol, tobacco, detection of depression scale, and financial compensation. A clinical and radiological follow-up took place at 6 weeks, 3 months, 6 months, and 1 year. The main functional measurement tool is the Mayo Elbow Performance Score (MEPS) and the Disabilities of the Arm, Shoulder and Hand (DASH). 123 patients were included in the study. 114 patients required nonsurgical management. 102 patients completed the 1-year follow-up for the main outcome (89 for the DASH score). Two patients required an unplanned surgery and were excluded from analyses. At 1 year, the average MEPS was 96.5 (range, 65–100) and 81% of subjects had an excellent result (MEPS ≥90). The most constant factor to predict an unsatisfactory functional outcome (MEPS <90 or DASH >17) is the presence of depressive symptoms at the initial time of the study (P = 0.03 and P = 0.0009, respectively). This factor is present throughout the follow-up. Other observed factors include a higher socioeconomic status (P = 0.009), the presence of financial compensation (P = 0.027), and a high-velocity trauma (P = 0.04). The severity of the fracture, advanced age, female sex, and the nature of the treatment does not influence the result at 1 year. No factor has been associated with a reduction in range of motion. Most of the radial head fractures heal successfully. We identified for the first time, with a valid tool, the presence of depressive symptoms at the time of the fracture as a significant factor for an unsatisfactory functional result. Early detection is simple and fast and would allow patients at risk to adopt complementary strategies to optimize the result.