The 14-year follow-up of a female patient with Liddle's syndrome (LS), a rare disease characterized by hypertension, hypokalemic alkalosis, and negligible aldosterone secretion due to renin suppression, is described. The disease was diagnosed at the age of 10 months (youngest identification). The patient was repeatedly investigated during follow-up for plasma renin activity (PRA), plasma aldosterone concentration (PA), serum sodium and potassium (K) concentration, blood pressure (BP), somatic anthropometry, and mental development. Noteworthy results included: persistent low circulating K, PRA, and PA and high BP, coinciding with unauthorized withdrawal of the triamterene therapy. These findings are in keeping with the hypothesis that LS results from a pathogenetic disorder which is not correctable with age. The triamterene therapy was effective in correcting the endocrine and metabolic disorders as well as arterial hypertension, but did not prevent a deficit in mental and physical development. However, the information derived from this study allows further clarification of the clinical picture of the disease.