Objective: To measure the Lipid content and the fatty acid IFA) composition of breast milk as part of a nutritional survey of the essential fatty acid (EFA) status of 5 months old Congolese infants. Design: Cross sectional nutrition survey. Setting: A suburban district of Brazzaville (capital of the Congo). Subjects: A random sample of nursing mothers and their 5 months old infants (n = 102). Data collection procedures: The mothers were questionned on their socio-economic status, dietary habits, and their body mass index (BMI) was measured, Breast milk samples were collected from each mother. Milk lipid content and fatty acid composition were determined. Results: Compared with milk from various countries, Congolese women's mature breast milk was low in lipid (28.70+/-11.33 g/L) but rich in 8:0-14:0 FAs (25.97+/-8.17% of total FAs) and in polyunsaturated FAs (PUFAs), particularly n-3 PUFAs (2.39+/-0.68% of total FAs, mainly 18:3 and 22:6). This was associated with the frequent consumption of high-carbohydrate foods (processed cassava roots, wheat bread, doughnuts) known to enhance 8:0-14:0 FA biosynthesis, and with that of foods providing n-6 and n-3 EFAs such as freshwater and saltwater fish, vegetable oil, green leafy vegetables, and high-fat fruit (peanuts, avocado, bushbutter), These foods were traditionally and locally produced. Milk lipid content was negatively related with mothers' BMI (P < 0.01) and varied with the frequency of consumption of certain foods corresponding to distinct dietary patterns. Conclusions: Lipid content and FA composition of Congolese breast milk were dependent on mother's nutritional status. However, despite an adequate EFA composition of breast milk, partially breast-fed 5 months old Congolese infants probably did not get enough n-6 and n-3 EFAs from breast milk to meet their EFA requirements.