Dioxins are a most toxic compound ever studied by human until today. Their significant health effects involved all ranges of age, including infants due to exposure to contaminated breast milk. The objective of the study was to appraise the status of dioxin contamination in breast milk among postnatal mothers live in urban and suburban areas in Klang Valley. It was conducted as a cross sectional study involving 101 postnatal mothers who came for their infant second hepatitis B vaccination. The samples were analysed using High Resolution Gas Chromatography (HRGC) following the USEPA Method 8290. About 70.3% of the samples were found detected with dioxin congeners. More suburban mothers have positive breast milk dioxins compared to urban mothers, 100.0% and 67.0% respectively. Significant associated factors include high fat daily intake (p=0.013), high milk daily intake (p= 0.044), high meat daily intake (p=0.001), body mass index more than 30 kg/m2 (p=0.005), and body fat % of more than 26% (p=0.046). In conclusion, amount daily intake of fat diet, meat, milk, body mass index and body fat are significant associated factors for the present of dioxins in breast milk among postnatal mothers in Klang Valley. More suburban mothers contain dioxins in their breast milk, which poses higher risk of health problems among their infants. A comprehensive study need to be conducted and regular followup need to be established in monitoring the future severity of maternal breast milk contamination to ensure the health of the next generations.