[Treatment of phenylketonuria: wish and reality].

A diet strictly low in phenylalanine from soon after birth on can protect patients with phenylketonuria against intellectual and psychomotor retardation. Our study tries to answer the questions how the patients and their relations cope with the diet, and weather they reach the serum-phenylalanine-limits recommended by the German Association of Pediatric Metabolic Diseases in 1990.