Secretory and membrane proteins from mammalian cells undergo post-translational modifications, including N-linked glycosylation, which can result in a large number of possible glycoforms. This sample heterogeneity can be problematic for structural studies, particularly X-ray crystallography. Thus, crystal structures of heavily glycosylated proteins such as the HIV-1 Env viral spike protein have been determined by removing the majority of glycans. This step is most frequently carried out using Endoglycosidase H (EndoH) and requires that all expressed glycans be in the high-mannose form, which is often not the native glycoform. With significantly improved technologies in single-particle cryoelectron microscopy, we demonstrate that it is now possible to refine and build natively glycosylated HIV-1 Env structures in solution to 4.36 Å resolution. At this resolution we can now analyze the complete epitope of a broadly neutralizing antibody (bnAb), PGT128, in the context of the trimer expressed with native glycans. •Natively glycosylated HIV-1 Env trimer solved to 4.36 Å resolution by cryo-EM•Complete description of the epitope of broadly neutralizing HIV-1 antibody PGT128•Multi-branched oligomannose glycans can be visualized and modeled by cryo-EM Env is the heavily glycosylated fusion machinery of HIV-1. Using cryo-EM, Lee et al. present an atomic model of broadly neutralizing antibody PGT128 in complex with a fully glycosylated Env that reveals the native, intact epitope.