There is a controversy wheter central pontine myelinolysis can complicate either hyponatremia or its rapid correction. We report a 69 years old woman with a history of one month of vertigo, nausea, vomiting and diarrhea. She was admitted dehydrated ad stuporous, and initial laboratory values showed a serum sodium of 96 mEq/L She was treated with dextrose 5% and 3% NaCI. Serum sodium raised to 120 mEq/L at the next day and the level of consciousness improved. At the 4th day of admission, the patient was again stuporous and with spastic quadriplegia. A magnetic resonance imaging showed a central and symmetrical pontine lesion on T1 and T2 weighed images. Thereafter, the patient experienced a progressive improvement of her neurological condition and was discharged three months later, moving her lower limbs. Nine month later she was able to walk. (Rev Méd Chile 2001; 129: 427-32)