The content of phenolic compounds was evaluated in powders of six Amazonian vegetables and their effect as a phytobiotic additive for post-weaning pigs. We used 18 castrated male piglets from the commercial crossing (Landrace x Duroc x Pietrain) of 25 days of age with an initial average live weight of 9.17 ± 1.89 kg, which were distributed according to a completely randomized design in three treatments with six piglets each. The treatments consisted in T0: Basal Diet (BD) without Growth Promoter Antibiotic (GPA); T1: BD without GPA + inclusion of 0.5% foliage powder of guava; and T2: BA without GPA + inclusion of 1% foliage powder of guava. The piglets fed the T2 treatment had the highest final weight (P<0.05), and the lowest incidence of diarrhea (P<0.0001), respectively. The foliage of guava, wild anise, wild garlic, sacha inchi seeds, Chinese potato tubers and orito banana fruit had an appreciable content of phenolic compounds. The inclusion of 1% guava foliage powder in the diet improved the final weight and reduced the incidence of diarrhea in post-weaning pigs.