This study examined rebound insomnia after discontinuation of chronic use of zolpidem (10 mg), a short elimination half-life imidazopyridine. The zolpidem group was bracketed by a placebo group and a positive control group taking 0.5 mg of triazolam (twice the recommended dose), which is known to produce rebound insomnia. Ninety-nine patients with sleep complaints that were polysomnographically documented participated in the study. After randomization, patients completed a 2-night, single-blind, placebo baseline period, a 28-night double-blind treatment phase, and a 3-night, single-blind, placebo substitution period. Polysomnographic and subjective sleep variables indicated a lack of rebound insomnia for the zolpidem group. The positive triazolam control group had rebound insomnia only on the first discontinuation night. There was no significant correlation between rebound insomnia and the level of initial insomnia, the degree of response to treatment in week 4, or the amount of tolerance that developed during drug use. During the 4-week treatment period, efficacy diminished for both drugs. From these data, it cannot be determined whether the lack of rebound insomnia with zolpidem is a result of drug dose or some property of the drug such as receptor selectivity.