【Objective】 To analysis nutritional problem in children with phenylketonuria treated with dietotherapy,so as to provide a basis for intervention. 【Methods】 46 children with phenylketonuria detected by neonatal screening in Qingdao were studied and compared to 61 matched normal children born at the same time. Nutritional state of the children was evaluated on the blood biochemical parameters,analysis of amino acids in serum respectively. 【Results】 1)The blood Zn,Cu in children with phenylketonuria were lower than those of the normal controls(P<0.05). Zinc deficiency in children with phenylketonuria was significantly higher than the normal controls(χ²=7.017,P=0.008).2)There were significant differences in blood aspartic acid, methionine, phenylalanine, argine, citrulline, glycine, ornithine between children with phenylketonuria and the controls(P<0.01).3)The free carntine,acetylcarnitine,propionylcarnitine and butylcarnitine were no significant differences between the two groups(P>0.05). 【Conclusions】 The present findings strongly suggest that there were nutrient deficiencies in children with phenylketonuria, though having been early-diagnosed and early-treated. Timely identification and correction of the nutrient deficiencies in children with phenylketonuria are important. To seek the best treatment program is the direction of our efforts.