Three patients with glycogen storage disease type I (GSD-I), three with glycogen storage disease type III (GSD-III) and one with pyruvate carboxylase deficiency (PCD) could be successfully switched over from continuous nocturnal gastric drip feeding (GDF) to nocturnal feeding with uncooked cornstarch in yoghurt or "quark" (CSF) at the age of 4-20 years. The new kind of therapy is much more convenient for the patients. When followed up to 30 months, patients on CSF showed the same clinical and laboratory findings as during the last two years with GDF. CSF was not introduced to three patients with GSD-I. Two of them refused the permanent starch-yoghurt meals. In the third patient the morning blood glucose concentrations were too variable.