This study conducted to investigate the effect of school lunch prgram on the blood composition of 50 children at the age 11 to 12 years old. Concentration of serum total protein, albumin, zinc and copper were measured at the begining of school lunch program(pre-feeding group) and at the one year later taken school lunch program(post-feeding group). Serum total protein and albumin concentrations in post-feeding group were higher than those in pre-feeding group, but showed no significant difference between groups. While serum zinc and copper concentrations in post-feeding group were significantly lower than those in pre-feeding group. Results indicated that school lunch program effective for improvement of potein nutrition in school children and it is nessessary futher investigation to disease the concentrations of serum zinc and copper in this age.