Background: An appropriate supply of n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) during early childhood may enhance cognitive development. Little attention is paid to the fatty acid (FA) supply during the complementary feeding period. We examined the polyunsaturated fatty acids (PUFAs) and LC-PUFAs pattern in dietary practice of two study groups and evaluated the results against the present Dietary Guidelines in Germany. Methods: The food consumption and FA pattern of dietary practice in subjects from two prospective studies (n ¼ 102 and n ¼ 184, respectively) at the age of 3, 6 and 9 months was assessed by weighed diet records, and changes during the first year of life were compared with the food-based dietary guidelines for the first year of life. Results: Dietary practice in the complementary feeding period was clearly dominated by commercial food products. The FA composition in dietary practice was different from the Guideline Diet and the ratio of n-6/n-3 PUFAs was less favorable. Consumption of breast milk or formula was still of major importance for the intake of LC-PUFAs in the complementary feeding period. Conclusion: LC-PUFAs are predominantly provided by breast milk and formula during the first year of life and consequently decrease when milk consumption decreases. For compensation, commercial complementary food might come closer to the Guideline Diet by lowering the n-6/n-3 PUFA ratio through appropriate vegetable oil along with an increase in total fat content up to the legal limit.