Hyaloperonospora is a genus of oomycete, obligate, plant pathogens that was originally considered to be part of Peronospora.

[1] Species in this group produce a disease called downy mildew and can infect many important crops.

[3] Later, Göker et al., also used molecular phylogenetic techniques showing that the group was different enough from the other Peronospora species to be its own taxon.

[1] Hyaloperonospora parasitica is unlike most other species in the family in that it has a very wide host range, infecting a variety of crops[citation needed].

Hyaloperonospora differs from Perofascia in that its sporangiophores are tree-like, its haustoria are lobate to globose, and the walls of its oospores are relatively thinner.

[1] The life history does not differ from that of Peronospora, the genus that Hyaloperonospora species used to be classified under[citation needed].