Endo H and F 1 are endoglycosidases that cleave the oligosaccharide moiety of asparagine-linked glycoproteins by hydrolysis of the glycosidic bond in the N,N′-diacetylchitobiose core. The two enzymes are specific for high-mannose oligosaccharides. Here, we report the crystallization and preliminary crystallographic analysis of Endo H and Endo F 1. Crystals were grown by hanging drop vapor diffusion methods. Both proteins crystallize from crystallization buffers containing polyethyleneglycol 8000 and zinc acetate as precipitating agents in cacodylate buffer. The crystals of Endo H belong to the tetragonal space group P4 12 12 (or P4 32 12) with cell dimensions: a = 85·22 Å, c = 89·41 Å. The crystals of Endo F 1 belong to the hexagonal space group P 6 1 (or P6 5) with cell dimensions: a = 70·61 Å, c = 100·32 Å. Crystals of both proteins diffract to at least 1·8 Å resolution.