ABSTRACT Azotobacter vinelandii is a Gram negative that undergo a morphological and physiological differentiation process to form cysts resistant to desiccation. The main components of a cyst are alkylresorcinols (ARs), phenolic lipids of 21 to 23 C. These lipids are homologous to plant ARs, where they have been reported to have antifungal properties. The objective of this study was to evaluate the antifungal capacities of vegetative cells and cysts of A. vinelandii AEIV. The cysts were visualized by optical microscope and the detection of ARs was performed by thin layer chromatography. Antagonism bioassay were carried out between vegetative cells and cysts against Fusarium brachygibbosum, Aspergillus niger and Colletotrichum gloeosporioides. We confirmed the induction of cysts and the presence of ARs of A. vinelandii AEIV. We observed that using 1×103 cysts reduced up to 76.3% (p < 0.05) the growth of the three phytopathogenic fungi and this result was not observed when using vegetative cells or the strain blocked in the synthesis of ARs. This shows that the cysts exert an antagonistic effect on phytopathogenic fungi and do so through the ARs, considering the development of an effective strategy to control pests in fungi that affect postharvest fruits.