Trace elements of Fe, Cu, Zn, Mg, Cr, Cd and Ni in Serum were assayed in fasting blood of 334 children ranging from 6 months to 6 years in Jinan City from Dec. 1988 to Jan. 1989. As the result, serum Mg,Cr, Cd,and Ni of all 334 cases are in the normal range. The prevalance of zinc deficiency is 36%, iron deficiency 24% and coppor deficiency 7 %. The younger the age, the higher the prevalence. Factors that influence the prevalences are diseases, feeding modes, sorts of auxillary foods, etc. Deficiency of Zn,...