This study of the body burden and serum concentrations of organochlorine compounds (OCs), represents a general population in a cohort from Menorca Island (birth 1997–1998) of children at birth and at 4 years of age; the study has shown that the concentrations of hexachlorobenzene (HCB), 4,4′-DDE, 4,4′-DDT, polychlorobiphenyl (PCB) congeners #153, #138 and #180 and total PCBs in sera collected at 4 years are much higher in breastfed children than in those fed with formula, e.g. HCB 0.48 vs 0.21 ng/ml, β-HCH 0.32 vs 0.24 ng/ml, total DDTs 2.2 vs 0.57 ng/ml and total PCBs 1.4 vs 0.52 ng/ml. Comparison of gender differences in 4 years old children shows higher concentrations of all examined OCs in females than in males with the exception of HCB and PeCB in breastfed children, which are higher in males than in females, e.g. β-HCH 0.34 vs 0.28 ng/ml, total DDTs 2.6 vs 1.7 ng/ml and total PCBs 1.6 vs 1.0 ng/ml for breastfed children and β-HCH 0.23 vs 0.19 ng/ml, total DDTs 0.59 vs 0.48 ng/ml and total PCBs 0.58 vs 0.45 ng/ml for formula fed children. Gender comparison of the body burden between children fed with breastmilk or formula also shows higher concentrations in females than in males, e.g. β-HCH 0.47 vs 0.35 μg, total DDTs 3.0 vs 1.8 μg and total PCBs 1.9 vs 1.2 μg for breastfed children, and β-HCH 0.39 vs 0.17 μg, total DDTs 0.48 vs 0.27 μg and total PCBs 0.66 vs 0.55 μg for formula fed children. The results may suggest a higher capacity in female children for the retention of OCs incorporated through breastfeeding. However, these results should be taken with caution because the differences of the gender averages have low statistically significance when evaluated with the Student test.