We studied 153 children who experienced convulsions associated with shigellosis. The male-female ratio was 1.2:1.0. Thirty-six children had a previous history of febrile convulsions, and 31 children had a family history of convulsive disorder. Most of the children were 0.5 to 3 years of age, although 49 (32%) were older than 3 years of age and 20 (13.1%) were older than 5 years of age. All children were febrile; in 75% of the children, the temperature was over 39 degrees C. The majority of the children had generalized, self-limited convulsions, which lasted less than ten minutes. In 30 children the seizures were categorized as complex; ten of them had recurrent episodes, although none had any residual neurologic deficit. The total leukocyte count was usually within normal limits, but the differential count characteristically showed a marked increase in the number of band forms. Hypocalcemia (blood calcium level, less than 9.01 mg/dL [less than 2.25 mmol/L]) was observed in four patients; hyponatremia (blood sodium level, 130 mEq/L [130 mmol/L]), in 11 patients; and hypernatremia (blood sodium level, 157 mEq/L [157 mmol/L]), in one patient. Electroencephalographic (EEG) studies were performed in ten children, and lumbar punctures were performed in 34 children; both procedures usually yielded normal results. Shigella sonnei was isolated from 69% of the children; Shigella flexneri from 25%; Shigella boydii from 5%; and Shigella dysenteriae from 1%. Due to the benign and self-limited nature of most of the convulsions, neither diagnostic procedures, nor drug therapy, are usually necessary. These measures should, however, be considered in complicated cases characterized by focal or prolonged seizures.