This overview shows the present state of the art in the treatment of glycogen storage diseases (GSD) illustrated by some characteristic courses of glucose-6-phosphatase deficiency (GSD type I) and of phosphorylase b-kinase deficiency (GSD type VIa). In the majority of our patients suffering from GSD type I the combination of nocturnal gastric drip feeding (GDF) using oligosaccharides with frequent daytime meals using high amounts of glucose, it's polymers and low amounts of uncooked starch is better accepted and more effective than a round the clock diet using high amounts of uncooked starch without the use of GDF. In one of three patients suffering from GSD type VIa dextro-thyroxine has been shown to be very effective concerning linear growth velocity, liver size, hyperlipidaemia and hypertransaminasaemia. Finally, the need and availability of prenatal diagnosis is discussed in view of the rather limited therapeutical efficacy in most of the GSD.