Jaeken's syndrome or the carbohydrate-deficient glycoprotein (CDG) syndrome, is a newly recognized metabolic syndrome with poor weight gain in children, and multisystematic abnormalities, mainly due to defective carbohydrate entities in many glycoproteins, leading to neurologic dysfunction. Using the standardized method of phenotype evaluation with computer assistance according to the Munich Dysmorphologic Database, two sisters with CDGs were examined to decide if this metabolic entity contains dysmorphic features characterising dysmorphic syndromes. Diagnosis was based on clinical symptomatology and transferrin isoforms which showed tetrasialotransferrin deficiency and increased disialotransferrin in serum. Dysmorphic studies can be helpful in recognition of this syndrome, now described for the first time in Poland.