We studied risky decision making (RDM) in 8 healthy adolescents (TC) and 11 adolescents with mild to moderate traumatic brain injuries (TBI) using the Balloon Analog Risk Task (BART) and functional magnetic resonance imaging (fMRI). Participants inflated simulated balloons (with more points awarded to bigger balloons), which might burst at any time. Increasing brain activation levels were associated with increasing balloon size in a largely bilateral network, including cerebellar, inferior parietal, limbic, and frontal areas. Both groups performed similarly and activated similar networks.