Hyponatremia and hyperpotassemia occurring in the first few weeks of life primarily indicate aldosterone deficiency due to salt-losing congenital adrenal hyperplasia (SL-CAH), while mineralocorticoid deficiency and insensitivity are the main causes of hyponatremia and hyperpotassemia in older infants. Some patients who present with vomiting and poor sucking, who have hyponatremia and hyperpotassemia and are initially diagnosed as CAH, during follow-up, are found to suffer from pseudohypoaldosteronism (PHA). This situation has been reported several times before. The cases described here represent the opposite situation: they presented with hyponatremia and hyperpotassemia, thus PHA was considered as aldosterone levels were very high, but subsequent investigation and genetic analysis led to the diagnosis of SL-CAH.