Introduction. The status epilepticus a serious complication of the epileptic syndrome with high rates of morbidity and mortality. Treatment is aimed to a fast control of the crisis. Aim. To evaluate the efficacy and security, of intramuscular (IM) midazolam in the initial treatment of status epilepticus. Patients and methods. A prospective open clinical trial that included 43 status epilepticus in 38 adult patients. All of the cases received an initial dose of 15 mg IM of midazolam, with a simultaneous oral dose of phenytoin (15 to 20 mg/kg) or carbamazepine (15 mg/kg). If there was immediate control of the seizure but recurrence occurred during the next hours, 15 mg IM of midazolam ever), 8 hours were given, for 24 hours. If there was immediate failure intravenous (IV) midazolam was given. Results. 36 of the 43 status epilepticus were controlled: 30 with only one dose, 3 required additional IM doses, and 3 needed administration of IV midazolam, no patient had neither cardiovascular, respiratory, or local complications. The only adverse effect was drowsiness in a variable grade. Conclusions. The use of IM midazolam is suggested as the initial treatment in status epilepticus in adults, especially in a low complexity setting, due to its effectiveness, quick action and security.