Objective. To determine the acceptability of purified fish protein (FPi) in cereal and pseudocereal-based drinks. Materials and Methods. The study was carried out at Centro de Desarrollo Integral Familiar “Año Nuevo” belonging to the INABIF Program in the district of Comas in Lima. FPi (0-4 g per serving) was administered daily for 3 months mixed with cereal and pseudocereal-based drinks. The acceptability of FPi was measured by direct weighing in children under 6 years of age and by the hedonic facial scale in school-age children. Results. One hundred and fifty-eight (158) participants were enrolled and 4,211 breakfasts were served. The caloric intake of the cereal and pseudocereal drinks, after adding the FPi, ranged between 117 and 140 Kcal, and protein intake ranged between 3.4 g and 5.4 g per serving. The acceptability of drinks supplemented with FPi in children older than 6 years of age (the 2 highest scores together) ranged from 55% to 74% for oats, around 47% for quinoa and 40% to 58% for “kiwicha” (amaranth). Whereas 90% of children under 6 consumed more than 70% of the drinks offered. Conclusions. We found a good acceptability of FPi in cereal and pseudocereal beverages in children under 6 years of age. FPi is an alternative to improve the consumption of animal protein in the nutrition of children, especially in pre-schoolers.