Objective: To evaluate the efficacy and tolerability of diazepam (DZP) rectal gel (Diastat; Elan Pharmaceuticals, Dublin, Ireland) for the treatment of acute repetitive seizures in adult patients in 2 multicenter, double-blind, placebo-controlled parallel studies. Methods: Ninety-six adults 18 years or older with acute repetitive seizures, 70 of whom received treatment, were randomized into the 2 studies. Active and placebo medications were supplied in prefilled, identical-appearing delivery systems. In study 001, patients received a second dose 4 hours after the initial treatment. Patients in study 003 received only 1 treatment. Patients were observed for 12 hours after the first dose. Results: There was a significant reduction in seizure frequency in patients who received DZP compared with the placebo group. The median number of seizures per hour in the group treated with DZP rectal gel was 0.00, vs 0.13 in the placebo group (P = .002). In addition, significantly more DZP rectal gel - treated patients remained seizure-free during the 12-hour observation period (71% [22/31] vs 28% [11/39]). Using Kaplan-Meier life-table analysis, time to the next seizure was found to be significantly longer in DZP rectal gel - treated than placebo-treated patients (P<.001). Global assessment as provided by the caregivers was in favor of DZP rectal gel for both study 001 (P = .17) and study 003 (P = .02). Dizziness and somnolence were the only central nervous system adverse events that occurred more frequently in patients receiving DZP rectal gel than in those receiving placebo. Conclusion: In adults, rectal DZP formulated as Diastat significantly reduced the likelihood of seizure recurrence during an episode of acute repetitive seizures, with minimal safety concerns.