Buspar (buspirone) is an anxiolytic medication used to reduce symptoms associated with anxiety. The current study provides a case description of a man diagnosed with autistic disorder where Buspar was prescribed on an "as needed" basis in order to decelerate tantrum behavior associated with undifferentiated anxiety. After successful reduction of tantrum behavior over time, caregivers reported a routine drug-effect time of less than 5 minutes. With consent through the individual's employer's governing human rights committee, a placebo pill was administered in place of the Buspar in the man's work environment. The placebo has successfully maintained reduction of the tantrum behavior. Given that the experimental treatment is less restrictive on the individual than the previous treatment, a treatment reversal was deemed unethical. Theories of mechanism and maintenance are discussed, as well as limitations to the current study. Directions for future research and implications for adults with autism are also reviewed. (Contains 2 figures.)