PURPOSE: Convulsive status epilepticus induces disturbance in acid-base homeostasis. It is known that metabolic acidosis is common after status epilepticus. A recent, discovery indicates respiratory acidosis is common after status epilepticus. This study is to analyze the acid-base disturbances in patients with status epilepticus. METHODS: Retrospectively, we reviewed twenty-five patients with status epilepticus, who were admitted to the pediatric department of Chosun University Hospital between January 1995 and August 2000. We have analyzed the clinical correlation among the acid-base disturbance, the incidence of pulmonary infiltration, and the type and duration of convulsions. RESULTS: Acid-base disorders in the status epilepticus were revealed in 17(68%) of 25 patients. Respiratory acidosis with or without metabolic acidosis was most common(N= 13; 52%). There was no significant correlation between the pulmonary infiltration(N=8; 32%) and the acid-base disorders(P>0.05). The most common seizure type in status epilepticus was generalized tonic clonic(72%). In that type, the most common acid-base disorder was respiratory acidosis(11/18). The mean serum pH was significantly decreased with duration of seizures(P<0.05). CONCLUSION: This study finds that respiratory acidosis with or without metabolic acidosis was most common in status epilepticus. There was no significant correlation between pulmonary infiltration and acid-base disorders. Respiratory acidosis was most common in generalized tonic clonic seizure.