The aim of this study is to report our 3years experience with the screening of congenital disorders of glycosylation. A common isoelectric focusing method with immunofixation was used for analysis of serum transferrin and α1-antitrypsin, apart from several other procedures. A group of about 1000 individuals, both healthy controls and patients, mostly with signs of a metabolic disease were examined. Here we present an overview of 1) hypoglycosylation findings, 2) distribution of protein variants, 3) misguiding rare Tf variants found in our set, and 4) association of some phenotypes with various diseases.