Both personality factors (e.g. impulsivity) and structural game characteristics impact decision-making on games of chance. We examined the relationship between impulsivity and decision-making on a slot machine task programmed with different near-miss frequencies. Fifty-eight college students entered a simulated casino environment and played a slot machine pre-loaded with 30 credits. Unbeknownst to participants, the slot machine was programmed so that several larger wins occurred early in the sequence, followed by a pattern of diminishing returns that reduced credits to zero on a predetermined trial. Participants were randomly assigned to two conditions, the first with up to 19% of trials set as near misses and the second with only 2% as near misses. After controlling for gender, race, and lifetime gambling frequency, the near-miss condition was found to moderate the relationship between impulsivity and the number of trials played. When there were fewer near misses, impulsivity did not appear to impact decision-making. However, when near misses were frequent, individuals with higher impulsivity persisted longer, even when other characteristics of gameplay remained constant (e.g. bet size, prizes). These findings suggest that certain features of slot machines may capitalize on impulsive gamblers’ vulnerabilities and should be regulated.