Maladaptive decision-making under risk is a feature of various neuropsychiatric disorders, yet the underlying neural circuits remain largely unexplored. The orbitofrontal cortex (OFC) is a main region for action-reward updating and flexible behaviors, is likely to play in this process. Our study aimed to investigate the role of the OFC in decision-making under risk. We developed a task requiring rats to choose between a safe option leading to a modest gain and a risky option which may earn a larger, but not guaranteed reward. Different probabilities were associated with the risky option so that it was either an optimal or a suboptimal choice. Our behavioral results revealed that learning to adapt choices under the high-risk condition, i.e. when the safe option is optimal, takes longer compared to the low-risk situation which favor the risky option. Additionally, trained animals demonstrated a temporary difficulty to disengage from the risky option several weeks after the learning phase, supporting the challenging feature of choices under high-risk condition. Post-training NMDA lesions in the OFC resulted in a transient impairment in the ability to adapt choices according to risk, particularly when the risky option was optimal. Moreover, OFC-lesioned animals exhibited slower risky decision-making and were more risk-adverse than sham-controls. Considering the functional heterogeneity of the OFC relative to adaptive behaviors, further experiments are in progress to better delineate the involvement of the OFC subregions in the learning of optimal decision-making under risk.