given the monotony and extended driving periods inherent in transport truck driving, truck drivers might rely on stimulants to sustain attention and combat fatigue. research indicates stimulants improve some cognitive functions but impair driving ability, and stimulant use is common among truck drivers. in addition, stimulant use is linked to collisions. research to date on collision culpability among stimulant-positive truck drivers is sparse and presents with limitations due to small sample sizes and a lack of control over confounding variables. the present study investigated the influence of stimulants on unsafe driving actions (udas) in collisions. the odds of being stimulant-positive were expected to be statistically significantly higher for drivers who committed at least one uda that led to a collision. using the fatality analysis reporting system (fars) database, the author compared truck drivers who had at least one uda recorded to a control group of drivers who had none. logistic regression was used in order to account for the influence of confounding variables (age, previous driving record, and other drug-use) and to calculate the odds ratio of being stimulant-positive in the event of an uda. results indicate that the odds of being stimulant-positive are statistically significantly greater for truck drivers who committed an uda (or 2.29, 95% ci 1.7-3.0). in addition, pearson’s chi-square models indicated stimulant-positive truck drivers were significantly more likely to have a history of infractions on their driving record and to have other drugs in their system. the results suggest stimulants negatively influence driving ability and truck drivers should not use stimulants while driving. in addition, the results support the inclusion of previous driving record and other drug use data as control variables for future studies. despite this, the finding that 0.58% of truck drivers in the fars database tested positive for stimulants suggests that stimulant use is not common.