The purpose of this study was to determine biochemical parameters related to protein and immunity. Subjects were 125 preschool children(M:69, F:56) residing in low income area of Seoul. Mean serum total protein of the children aged 6 was 7.3g/dl which was significantly higher than 6.6g/dl of the group aged 3. The mean serum albumin was 4.7g/dl for 3, 4, 5 age group, and 4.9g/dl for 6 age group and there was no significant difference. Serum retinol binding protein(RBP) is used as a sensitive indicatior of protein, because it tends to fall rapidly in response to protein status and respond to quickly dietary treatment. Mean RBP for each group(3, 4, 5 and 6 age group) were $2.5mu{g}$/dl, $2.9mu{g}$/dl, $2.7mu{g}$/dl, $3.0mu{g}$/dl. The Proportion of children whose RBP was than $2.6mu{g}$/dl was 15.9%, 19.2%, 24.3% and 16.7%, respectively. The 24-hour urinary excretion of hydroxyproline was 7.9mg, 14.6mg, 11.7mg and 11.8mg for each group and the mean excretion of all children was 12.2mg/day. Children aged 3 were excreting significantly lower amount of hydroxprolinc per day than the children aged 4. The mean hydroxyproline index were 2.18, 2.39, 2.52, 2.80 for each age group and the mean of a group aged 6 was significantly higher than that of the group aged 3. The proportion of children assessed as malnourished and impaired growth(hydroxyproline index <2.0) was 18.8%, 4.9%, 2.5% and 4.3%, respectively. The nutrients which showed significant relationship with protein and immunity parameters were niacin, vitamin C and calcium. Vitamin C showed significant positive relationship(p<0.05-p<0.01) with serum RBP, total protein and globulin. The triceps skinfold thickness was significantly and positively correlated with serum globulin. Serum IgG showed significant positive relationship with height, weight, girth of chest and midarm circumference(p<0.05-p<0.01).